Cathy,
Without being able the see the machine here's my take on what you said. (Pics of the hand wheel end and bottom would be a lot of help.)
The main drive belt has become worn and probably stretched. If it's not cracked you should be able to adjust it.
There should be either screws or a cam like affair on the motor mount that moves the motor away or towards the top shaft. You'll see it either when you pull the end plate off and or when you turn the machine on it's side.
If so then carefully tighten the belt a little bit. Leave some slack, you don't want it too tight.
If you can remove the belt from the main shaft when you remove the hand wheel, and there's nothing in the way down below, you can replace it yourself.
Some of them however require a lot of dissassembly just to get the belt off. I won't even touch one of those. Well, not yet anyway.
Also while you're in there, oil it reallllllllly good.
Joe