The Incline is stuck at an angle

1) You have problem with LUBE deck belt, this happen because the lack of maintenance, you must lube EVERY week, use 100% silicone lube. Maybe you have WORN deck belt,
2) LUBE the rollers bearing too, use wd-40
3) Test the drive belt motor, see for break, or worn, and replace or tension by 1/4"
4) Test the input voltage motor, if there are the motor need repair. see my personal TIPS for help and troubleshooting.
5) Test the output voltage board, for input voltage motor, if there are NOT the board controllers is faulty. God bless you. see the block diagram attached.

Watch the videos:
http://www.youtube.com/watch?v=TquYcOzGIw4&feature=related
http://www.youtube.com/watch?v=9G4MZh8JO2Q
http://www.youtube.com/watch?v=M7qJrRbdfBc
http://www.youtube.com/watch?v=MIIxoPtvhy8
hthttp://www.fixya.com/support/r10724803-measure_voltage_in_transforme_fitness http://www.youtube.com/watch?v=bF3OyQ3HwfU&feature=related

Try to recalibrate the incline. Start the machine running, press the incline up button, then pull the safety key off. Release the incline up button and replace the safety key. The treadmill should go to maximum incline then minimum. after calibration is completed, retry the treadmill operation.

First try to calibrate the incline as described in your owners manual.
Start the machine. Press the incline up button. While pressing the button, remove the safety key.
Release the inline up button and reinsert the safety key. The machine should run the full cycle, up to maximum elevation, then back down.
If the motor moves and then resets, you may have an incline motor sensor defect. You will need to order a new incline motor. The sensor is not available separately..

Did you make sure the incline is completely down? I had a similar problem and then realized the incline was on 2. I recalibrated and then it latched fine.

push it forward before trying to pull knob and make sure the incline is at the lowest level.

Usually when stuck at the max up position it indicates that you may need a new incline motor. It is not the sensor. I have been repairing treadmills for 15 years and incline sensors seldom if ever go bad. If can isolate the incline motor using a 110 volt power cord, this may un-jam the motor and get it back down to 0%.
I use www.treadmillpartszone.com for parts.

First foremost is the unit incline to zero degree if not power up the unit hit the start and use the quick incline zero button. Now if that does not resolve the problem check your latching assembly especially the knob and see if it locks in place or if the knob feels sticky then a little bit of 3 in 1 machine oil will do the job.

check and see if you incline is down to zero if not this problem occurs or the or plug it in and if the incline reset itself then it should be o k if not you may have to do a calibration on it

Check here for the user manual:
http://manualfox.com/link/reebok.htm

And maybe send them a manual request?