Tailgate window sluggish

OK I got the motor out and with the help of WD 40 and then 3 in 1 oil got the sucker spinning in both directions. I reinstalled it and it seemed to work well but after it sat for a while, it was difficult to get the motor to raise the window the last inch or two. I found that if I pulled the right top of the window outward, it gave enough play to allow the motor to close it completely. I used lithium grease on the gears and a nylon spray lubricant on the tracks as well as the rubber seal around the window. Should I go back in and spray everything in sight with silicone spray or is the motor just too weak? If that is the likely culprit, should I replace just the motor?
Any ideas for sources other than stealership?