power window question

[odee]

hello, I have an 56 gmc 2wd crew dually that I'm in the process of putting a cummins into. We have the truck in a driving state right now. Working on getting the power windows to work. None of the window will work. Haven't tried the locks yet. I have power and a ground at the switch,power leaving switch to the motor on driver door in up and down,also at motor with test light grounded to switch and door. Truck has sit about a year or so was told windows were working before I got it. Could motors have stuck from no use or just bad, missing something in the wiring? thanks