I bought an used treadmill (Proform 635CS). Its incline stuck at highest point. Every time I plug the key in, the incline motor made some noise and seemed the motor tried without moving.
If in this situation, the motor is not dead. It is stuck or jammed.
This is what I did:
1) I took the power cord off from power.
2) I took a cover off from the bottom of machine, so you can access the motor.
3) I unscrewed the bolt on one of end on the incline motor. At this end, it is usually a big screw like a shaft.
4) tried to make this screw turn. Mine is jammed, so it was not that easy to loose. I tried hard in both direction, so finally the shaft can be turned freely.
5) Without putting the motor back, connect all power back like normal, then put key into machine and tried to go up or down on incline motor. the more turned and worked like normal.
6) Then took of power cord from wall again and I put the motor back on the machine like I took it out. Then reconnected power to try, it works fine.
After I solve the problem, the incline motor got jammed again, then I repeat above steps with a big screw adjustment (loosing or tighten about 1/2 turn, it depends). Now the incline works fine.
SO my $50 bought used treadmill works like new.
Hope it will help.
chao, September 2007