newcomb R-12C record player

I have an old Newcomb R12-C from 1956 that I got as a basket case. The maroon covering was rotton along with some of the wooden case. After repairing the wood case with bondo where needed and recovering with the origional maroom vinyl or leatherette material, recapping the amplifier, replacing the speaker, the idler wheel and turrets, and cleaning and reassembling the motor, it sounds beautiful but after playing about an hour it slows down. Does anyone have any ideas? I have spent quite a few hours trying to resolve this. I do not have the origional spring for the idler wheel tension and have experimented with similar hardware store springs cut to different lengths. I am a new member and would like to take this oppertunity to say Hi to all.
Alan

Your motor is gummy. You need to take it apart, and, correctly clean the bearings of old dirty oil. After that is done, use a proper light synthetic high temperature electric motor lubricating oil in the bearngs, and, the part of the shaft that goes into the bearings. Caution, don't let any get on the main shaft, as it will then get the oil on your idler wheel, and, it will slip.

Also, the turntable bearings, and, the idler wheel shaft should also get a couple of drops of oil. Don't let any get on your drive surfaces, namely, the itler wheel tire, and, turntable rim, and, motor shaft.
Hope this helps.
Bill Cahill