I have 2 vanagons with power windows...

most problems are on the driver's side..  it's normal because more usage
than the passenger's side

most problems are:

- lack of lubrication

- poor design or wrong material used on the black curved bottom plastic
slider

- out of adjustments which put strain on the motor and the cable

I fixed mine twice on both van... but it's very tedious job .. about 4
hours just for take out and put back -  and you have to leave the van