I've had good results dealing with YS direct. If you know the part #'s you need, you can send them a note and ask via email
if they're still available. Good chance they are.
I've gotten parts / gaskets / diaphragm for a YS .45 from them direct. I also have a .61 LS and have a parts list for it.

Don't remember where I found the parts list or op manual for it, so I can't supply a link for that. But here's a link for ordering parts from Japan direct if it helps. They'll
reply to you within a day or two after sending it and let you know if they're still available.

https://www.mmjp.or.jp/ssl.yspower.co.jp/order_e.html