Hey Justin, nice score for 20 dollars on the TR-60! These things run better when they are cleaned out. Pull the filtrator cartridge out and feel up under the drum to see if it is stuffed full of lint. If so, time for a dust and clean! The front rollers will also probably need to be taken apart and re-lubricated. Just take off the four front screws around the door opening to take the front inner pannel off to get to the rollers. A sure sign that they need help will be a horrible rumble while rotating.
Hopefully the calrod-like elements are in good shape. Might want to take the back cover off prior to plugging it in to make sure all the cloth-covered wires are in good shape. The belt/s number is a 4L480, and if you need a replacement bearing for the drum, the Grainger item number is a 1L046 (NTN number 6005LLBC3/5C).
Let me know if you need anything else! Sorry, I don't have a replacement knob.
Ben