Power seat seat is stuck in high position motor seems to work but does not go down

If the other seat positions work ok, then it sounds like voltage and ground are ok.
I don't know what testing you've done?
The horizontal motor, to move back, lite green wire is voltage. tan wire is ground, need both. You can use a test light to check voltage and ground.
I don't how difficult to get at those wiring circuits? Some makes and models, I'll remove the seat to do testing. Then you can use jumper wires off the battery for the horizontal motor, if the motor is the problem. I can only help with testing.

If it's binding the circuit breaker will shut off the recline motor. You have to replace the entire back frame to replace the motor

if you look real close at the underdash fuse panel theres gonna be one labeled "power equipment group" that's the one you want to replace , but i'll tell you if you try and move the seat again its most likely gonna go again as I replace lots of power seats that have something (any object) stuck in seat track jamming up the motor

Yes, if you purchase a manual set is will bolt in just the same so long as its the same model and year as they do change from year to year.

It seems the hydrolic has stopped working. hydraulic's ???? The seat is electrically controlled - not hydraulic's Looking at wiring diagrams an testing the electrical circuit's is the way to find the problem . Could be the electric motor , switch ,wiring etc... Your best bet mite be to take your vehicle to a automotive electric shop.

I think that power seats are different than the manual seats fundamentally. So, if the motor stops working, it is stuck in that position until electrical repairs are made.

I don't think there is a manual lever override for any power seats that I have seen.

There are 3 motors mounted under the seat to move the postion of the seat, the cable for that motor maybe broken. Also check that the pivot points move freely and that there is nothing jammed in the seat tracks.

Had this same issue with my 2004 Expedition. I removed the seat, seat motor and seat track. I tested the motor by plugging back in but without the track and was spinning freely. Took the track to the Ford Dealer. Was able to speak to a service tech. Said it is not the motor it’s the track, it gets stuck if you move to the extremes of the up or down. It’s like over tightening a jar stuck and unable to open again. WHAT TO DO: there are to impellor rods the spin on both sides of the motor. The rods look like wound up springs. Reconnect the rods back in the track. Use your Electric drill to hold the other end of the to break free the stuck track by spinning the impellor rod. Do this for both side. make sure to align the rods properly before return the motor. Also, try not to fully extend the power seat to the very up or down of the track. This will keep from causing the stuck jar effect. ONE and DONE.. Hope this helps.

which maxi fuse gets hot ? # fuse , plus amps The power seats uses a 30 amp circuit breaker ,not a fuse . The horn gets power from the same circuit breaker . . Sounds like something is drawing to much current. Do you know how to use a amp meter to test current flow . Disconnect componets till draw goes away ? How to use a wiring diagram to pin point areas in a circuit to test ?
Is there corrosion on the pins where the seat circuit breaker plugs into ? Reach under your seats an see if one of the seat motors is hot .
DeVille
The left and the right power seat system consist of the following components:
• The seat switches
• The seat relay modules
• The 4 reversible motors:
- The front vertical motor
- The rear vertical motor
- The horizontal motor
- The recline motor
These 4 motors operate independently of each other.
When the entire seat switch is pushed to the FORWARD position, the forward input of the of the seat relay is grounded.
The seat relay module supplies battery positive voltage (B+) with a ground to the horizontal motor, in response to this input. In order to drive the seat forward, the motor runs until the switch is released.
The BACK position works similar to the FORWARD position with the exception that the voltage polarity supplied by the seat relay module is reversed causing the motor to run in the opposite direction. This action drives the seat backward.
These recline switches operate similar but independently:

The seat relay module could be bad , If you don't know how to do automotive electrical circuit testing it mite be a good idea for you to take your vehicle to a qualified repair shop.
Could have diagnostic trouble codes stored as well .
DTC B0846 +5 Volt Reference Out of Range
DTC B0856 Battery 2 Out of Range
DTC B1656 EEPROM Write Error
DTC B1658 EEPROM Checksum Error
DTC B1982 Source/Battery Voltage High
DTC B1983 Source/Battery Voltage Low
DTC B2101 Recline Aft Switch Failed (Eldorado)
DTC B2101 Recline Aft Switch Failed (DeVille)
DTC B2102 Recline Forward Switch Failed (Eldorado)
DTC B2102 Recline Forward Switch Failed (DeVille)
DTC B2103 Rear Vertical Down Switch Failed (Eldorado)
DTC B2103 Rear Vertical Down Switch Failed (DeVille)
DTC B2104 Rear Vertical Up Switch Failed (Eldorado)
DTC B2104 Rear Vertical Up Switch Failed (DeVille)
DTC B2105 Horizontal Aft Switch Failed (Eldorado)
DTC B2105 Horizontal Aft Switch Failed (DeVille)
DTC B2106 Horizontal Forward Switch Failed (Eldorado)
DTC B2106 Horizontal Forward Switch Failed (DeVille)
DTC B2107 Front Vertical Down Switch Failed (Eldorado)
DTC B2107 Front Vertical Down Switch Failed (DeVille)
DTC B2108 Front Vertical Up Switch Failed (Eldorado)
DTC B2108 Front Vertical Up Switch Failed (DeVille)
DTC B2109 Lumbar Aft Switch Failed
DTC B2110 Lumbar Forward Switch Failed
DTC B2111 Lumbar Down Switch Failed
DTC B2112 Lumbar Up Switch Failed
DTC B2115 Recline Sensor Failed
DTC B2116 Rear Vertical Sensor Failed
DTC B2117 Horizontal Sensor Failed
DTC B2118 Front Vertical Sensor Failed
DTC B2119 Lumbar Forward/Aft Sensor Failed
DTC B2120 Lumbar Up/Down Sensor Failed
DTC 2130 Seat Motor Failure