Who still has parts available? (For instance, Panasonic/Matsushita doesn't.
-----------Not really much if any.
What models can I more easily scavenge for replacement parts? ------------------------------Pioneer
Availability (used or otherwise) of proprietary service tools (reference discs and the like)?- -Pioneer
Others will chime in and I know very few parts are available, some have a few test discs and few grip rings but I think from
what I remember reading the grip rings are gone now.
Other than that you will have to salvage other players and Pioneer is your best bet.
Good luck and enjoy collecting LDs.