need help 1999 Jeep Cherokee passenger side power window

My passenger side power window began to rise and lower at a slow speed. Then one day it went down but would no longer go up. I physically raised it by hand but it will slowly lower via vibration and by running over bumps. I can hear the power window motor run if I engage either the driver side control or the passenger side control, but nothing happens to the window. Currently I keep the window up by placing a paper shim between the rubber weather strip and window. Anyone know what went wrong with the power window function and how I fix this thing?? Diagrams anyone?? Thanks in advance. Dan