Thanks Ohen. I have the tools and knowledge to do most of my own work with centerfire and rimfire, but I have no experience at all with air guns. Weihrauch's site contact info appears to be broken (sends me direct to their Instagram). I will keep looking.
I just acquired a used Weihrauch HW50 at a local auction. It's twangy and shooting at very low velocity. I'm guessing the seals are shot. Is there anybody near Frederick who repairs airguns?
Thanks!
John