The good news is that winches are ruggedly built and don't often require parts. The only thing I can think of you might need are pawls and springs - you might be able to modify Lewmar
parts. By the way, my Lewmar
winches are that old as well, and Lewmar doesn't carry parts anymore either (I can use other Lewmar pawls and springs), so don't feel too bad.
Your winches look identical to my Lewmars. It's possible that these are Japanese knockoffs of Lewmars - parts may be interchangable.
Winches are not too complex (though my 3-speeds are pretty packed with stuff), so I'd suggest taking the drum off and looking at them. Just remove the ring and pull off the drum, making sure no pawls fall out.
Incidentally, you can get used non-self-tailing winches pretty cheap
- I've seen a set of two Lewmar 55's like I have on my boat for $1200.
What kind of boat do you have that has Japanese stuff - Yamaha?