I had a similar type problem - you press the up button and all you here is grind... grind... grind... and no movement.

Here's how I fixed mine...

The window motor in the door has 3 plastic ***** in the gear mechanism that act like bearings. After years of use they get ground into little plastic shreds... thus motor turns but gear doesn't...That's the easy part.

A replacement motor unit is very expensive - but.... Ford sells a replacement gear set for $35 that won't work for our truck (or at least on a 93 F250) - but....

It has the same size plastic bearings that I needed - so I purchased it, removed the bearings, and used them in my electric motor.

The motor and arm assembly in my PS door is one piece assembly and mounted to the door with shoulder rivets. I drilled the rivets out, and very carefully was able to remove the assembly thru the opening in the door. (no need to remove windows or other hardware) - It's a bitch but you'll figure it out.

Once I had the assembly on the bench, I dis-assembled the motor from the track, and removed the gear cover, pulled the gears out and cleaned out the plastic "shrapnel" and replaced the three plastic *****, greased and re-assembled the unit.

I have a rivet gun but I couldn't find any shoulder rivets - so I used some 1/4 - 20 nut-sert rivets and riveted them into the motor/arm assembly on the bench. Carefully placed it back in the door and on the tracks, and used some very short 1/4-20 bolts and washers to re-mount. don't use long bolts or they will stop the arms from moving.. You'll see..

It's been working ever since. And that's how I fixed my DS power windows for under $40

Picks included in my post (but the three plastic ***** are gone - but I know you can figure out where they go!) ... not saying this fix will work for you.... Please let me know how it worked out....