The right side rear power window works but not quite right. It starts so come down then drops about 1/2 way. It can go back up using short moves and close ok. Any one else had this problem and the fix ? Thanks. *BW*

 

It sounds like either the regulator assembly is loose/worn/ broken, or the glass isn't sitting squarely in the seals and is fetching up as it travels up and down.
I'd put money on it being the regulator, and I'm not even a betting man.