For the past year or so the driver side rear vent window will not always open. Sometimes it works, sometimes not - hitting the motor or lever mechanism near the window does the trick - again, sometimes. It's the motor, not the switch.
Thinking it would cost me $100, I went to the dealer. Yep, they quoted Cdn$108 for the part "MOTOR, Window Regulator, Left, Quarter Vent Window Actuator" P/N 04874115. Thanks - I will keep on hitting it while trying the advice in another post (99 Caravan Rear window motor). Happily, JC's advice worked for me.
Access to the motor assembly is easy in the Caravan - pop off the 6x36 inch plastic trim above the rear door inside, then pull on the top of the plastic trim panel behind the window vent. Two spring-loaded clips pop out - that's it, now you can access the motor by removing the two hex-head bolts and the 2-wire harness clip.
Taking the assembly apart was fairly easy - I just pried with a knife blade and sharp chisel near the melted "rivets" and managed to pop it apart without breaking anything. I think it would be hard to crack the assembly seriously enough to damage it, it's made of black plastic (carbon fibre?) - just make sure to concentrate your prying at the melted rivet points. And don't open it too fast afterward, you will have a few gears all over the place.
The motor slips right out, with the worm gear attached. It is a Mabuchi RK-370C motor, you can find a spec sheet on Mabuchi's website
I used a flat-bladed screwdriver to carefully slide the wormgear off (but if you break it, you will be spending $108). The shaft on the new motors is only about 9mm (5/16"), but the wormgear seemed to slip back onto it okay with enough purchase, and friction-fit okay. I hope it doesn't break later, because the wormgear itself is longer than the new shaft by 3 or 4mm.
No soldering required - the motor just plugs into sockets inside the assembly. Pop the motor back in, close up the assembly temporarily and put it back in the car for a test - works great, way faster than the other one that still works! If the motor turns the wrong way, I think you would just take everything back out, flip the motor over, and re-test in the vehicle.
After everything is good, re-glue the plastic rivets and install the assembly back in the vehicle. Pop the panels back in, you're good to go.
FYI - I did disassemble the old motor and clean the contacts and brushes. It was still fairly powerless (but didn't stall anymore) even outside of the actuator assembly. I threw it away.