Post a picture, if you can. Someone here will have a link to a schematic. If you need parts you must realize that winch manufacturer has been out of business for decades. There was a parts source for the barlow/barient winches (
http://www.arco-winches.com/barient.php) based in australia that may still be viable....but I'm not sure.
The really good news is that West Marine is having their annual 2 for one sale on all Lewmar winches... so if you have about $1200 or so you can pick up a pair of 40's, self tailing, for your boat. I'd jump on it if I were you. I know it sounds like a lot but it isn't really.
You might find something on ebay, but don't get your hopes up. If you want inexpensive replacements, go with pre owned, standard (non self tailing). There will be plenty available from those people who upgraded because of the Lewmar/WM sale. In fact I have an excellent pair of Barient 24's. 2 speed, non self tailing, chrome over bronze. Really nice winches. Make me an offer. To figure shipping, they weigh in at 14 lbs a piece. A well cared for winch will last forever. That's why you never see used self tailing winches on the market.