The unit will not raise or lower. It will function but only in its existing position, which is at about 5% incline. I do not have an owners manual either.

https://www.lifespanfitness.com/fitness/resources/articles/what-does-your-treadmills-error-code-mean

E6 or E7 An E6 or E7 error code is an incline error code. The E7 code means the potentiometer value the console is reading from the lift motor is out of range. This can happen when there is a bad wire harness connection or a damaged wire harness. It could also just mean the incline motor needs to be adjusted back into range. If all wire connections look ok, the incline motor will need to be adjusted.

1. Turn the power OFF, wait 5-seconds and turn back ON.
2. Get into test mode and enter through the I/O testing step. This screen will display the potentiometer value of the incline motor. Different models will have different values. Check to see if the running deck is raised to high incline level or if it is at the low level. If the running deck is at a low position press the incline up button. This will cause the incline motor to raise the running deck up. When the deck gets to a mid-level position, press the incline up button a second time to stop the deck. If the running deck is in a high incline position, use the incline down button to adjust the deck to a mid-level position.
3. Once the unit is in the mid-level position, power the treadmill off for 5-seconds and then power it back ON.
4. Start the treadmill.
5. Once the treadmill starts the running deck will move to the level 0 position. If this does not resolve the issue or it will not adjust please contact customer service.

Also note that not all models will have the ability to adjust the incline motor. If the adjustment procedure is not found in the Owner's Manual then contact customer service.

For E6 and E7 codes, while this code is displayed:

First, press and hold Level Minus, then the Start key (the Level Minus key first), for 2 seconds. (make sure you press Level Down a little before Start.) The console should beep twice; the display does not change.

If the potentiometer value on the left of the screen is higher than 240, press and hold the Ramp minus key to lower the ramp until the value is in a range between 48 and 240. Then release the button. May reset by itself now. Or, turn the elliptical off and back on to reset. If ramp goes up to 255 and won't move in any mode, unplug power for 20 minutes.

If the potentiometer value is lower than 48, press and hold the Ramp plus button to raise the incline until the value is in a range between 48 and 240. Then release the button. May reset by itself now. Or, turn the elliptical off and back on to reset.

Now press Start, and pedal for 30 seconds. The ramp should reset to zero, the lowest level.

An E6 or E7 error code is an incline error code. The E7 code means the potentiometer value the console is reading from the lift motor is out of range. This can happen when there is a bad wire harness connection or a damaged wire harness. It could also just mean the incline motor needs to be adjusted back into range. If all wire connections look ok, the incline motor will need to be adjusted.

1. Turn the power OFF, wait 5-seconds and turn back ON.
2. Get into test mode and enter through the I/O testing step. This screen will display the potentiometer value of the incline motor. Different models will have different values. Check to see if the running deck is raised to high incline level or if it is at the low level. If the running deck is at a low position press the incline up button. This will cause the incline motor to raise the running deck up. When the deck gets to a mid-level position, press the incline up button a second time to stop the deck. If the running deck is in a high incline position, use the incline down button to adjust the deck to a mid-level position.
3. Once the unit is in the mid-level position, power the treadmill off for 5-seconds and then power it back ON.
4. Start the treadmill.
5. Once the treadmill starts the running deck will move to the level 0 position. If this does not resolve the issue or it will not adjust please contact customer service.

Also note that not all models will have the ability to adjust the incline motor. If the adjustment procedure is not found in the Owner's Manual then contact customer service.

sounds like there is problem in the console or the wire going to the console. the treadmill calibrates ok

Its showing e6

LUBE or wax the deck belt, this happen because you do not have schedule maintenance according with the owner manual. The machine shut down for autoprotection in electronic system Do it NOW.
2) LUBe the rollers bearint too with WD-40 only for rollers
3) Test the drive belt motor, for worn or cracking belt, replace or adjust it
4) Test the input voltage motor, if there are the motor need repair, see my personal TIPS for troubelshooting help.
5) Test the output voltage board, for input voltage motor, if there are NOT the board is faulty.
God bless you

incline Motor is not working it can be a few different things.
1) may not be any signal from the console which could be a damaged cable(tight the flexible cable from keypanel vs display board)
2) Tight the connector from display board vs lower board ( main motor controller board the console itself has failed.
3) The motor control board may have failed from a worn treadmill belt and deck measure 120VAC input for the board
5) the motor may have burnt out Test try to measure 120VAC.
6) potentiometer geared to the motor adjust it so the console knows what height the incline is at.
7) the gearing can slip, giving the console false information which can cause chassis damage.
Now see the block diagaram that I did , for person like you, for to know how the main motor board has aprox 90% of functions of any treadmills. sincerely. Good luck, G-d bless you.

E.CUADRA
MANAGUA, NICARAGUA. C.A.

E6 or E7 An E6 or E7 error code is an incline error code. The E7 code means the potentiometer value the console is reading from the lift motor is out of range. This can happen when there is a bad wire harness connection or a damaged wire harness. It could also just mean the incline motor needs to be adjusted back into range. If all wire connections look ok, the incline motor will need to be adjusted.

1. Turn the power OFF, wait for 5-seconds and turn back ON.
2. Get into test mode and enter through the I/O testing step. This screen will display the potentiometer value of the incline motor. Different models will have different values. Check to see if the running deck is raised to high incline level or if it is at the low level. If the running deck is at a low position press the incline up button. This will cause the incline motor to raise the running deck up. When the deck gets to a mid-level position, press the incline up button a second time to stop the deck. If the running deck is in a high incline position, use the incline down button to adjust the deck to a mid-level position.
3. Once the unit is in the mid-level position, power the treadmill off for 5-seconds and then power it back ON.
4. Start the treadmill.
5. Once the treadmill starts the running deck will move to the level 0 position. If this does not resolve the issue or it will not adjust please contact customer service.

Also, note that not all models will have the ability to adjust the incline motor. If the adjustment procedure is not found in the Owner's Manual then contact customer service. Treadmill Error Codes Troubleshooting

Hello there, The machine is attempting to do an incline calibration. Keep the unit lowered as you have it, reinstall the safety key, allow the unit to go all the way to the top and then all the way to the bottom. The machine will stop when at the bottom and the screen will go back to normal. The machine will not overtravel the incline motor and damage it. Just let the calibration finish the procedure and you will be fine.
Good Luck! Tim
FYI this will happen anytime the safety key is removed while the incline is moving on nordictrack brand machines.