Classic old gun. They were not expensive when new, hence not much $ value in them now.
Try Gunbroker.com for online auctions of parts. Lots of vendors with similar stuff, shoot them a private message, ya never know, they might have wot you need. Gunparts in West Hurley is another good one to try, they have a website.
It is loose because it is worn. I am sure it can be fixed, but you will need a smith or a machinist to make new oversize pins and things to tighten it. But if it works and locks fine, maybe just live with it with a bit of play in the thing.
