i kinda have that problem with my passenger rear window, it strains somtimes or it wont do anything at all i take the side panel off take the cover to the motor off spray some wd40 on it and it works fine till it trys up again or somthing comes loose again, then i gotta go redo it again but it dont take a good 5 min to take it all apart and put it back to geather.. Your motor could be going out aswell on that same window it makes alot of noise but thats cause the motor is getting old and wore out... good luck!