This gun has been shot a lot for several years. Without a chronograph I really didn’t expect that much damage. I thought I would maybe do something with the piston sleeve to prevent a broken spring. Michael your theory on the seal failure causing spring failure sounds right. I have always used lead pellets. I know seals wear out but Does this seal look like something normal wear that happens over the course of use or burnout from detonations ? I am sure it dieseled some but nothing excessive I remember. This is the first time this gun has been apart so I don’t know if the seal had a cut there when new that got worse ? Just a curiosity question. Never looked at a bunch of bad seals.Flying Dragon will have quality parts I need.
The Chinese clones of the Diana 34 have a clone of the T05 trigger so you should be able to drop in the Diana version with no issue. Rather than buying one though you could polish yours and do the second screw mod. The Diana T05 by the way only uses a single adjustment screw and could be a candidate for the second screw as well. It's hard to gauge how long a seal or spring will last. When it was only sixteen years old I disassembled my Diana 34 (purchased very used) and determined the piston seal had not yet broken in - it was far too tight. The gun still had the original spring. I turned the seal down for a better fit, though a couple of pounds of force were still required to move the piston. Accuracy improved significantly. That seal, by the way, has a small nick, probably user inflicted. The gun is still highly accurate.