Hi, newbie here, been lurking and reading for a while though. I am rebuilding a 1982 Diana Model 25 that was a gift from my Grandpa when I was a kid. Understand this model is nothing special but it has sentimental value for me. Gun was stored for 20+ years, after coming out of mothballs i promptly over-lubed the chamber (before finding this forum and reading up on proper maintenance), got lots of dieseling, possibly some detonation. Power was so low, you could see the trajectory of the pellet in the right light. Took it apart the other day (first time springer disassembly for me) and the piston seal looks shredded/burned in the center and will need to be replaced. Spring looks ok but is not dead straight so i figure i may as well replace that also. Umarex has all the parts.
Here's the main question: I understand that the JM R7 spring will also work in this model Diana, with some guide 'modification'. Wanted to find out exactly what modification would be necessary, or if an entirely new guide would need to be machined? Also if it's even worth it? Can anyone who has performed this modification shed some light here? Anything else i need to consider on this rebuild?
Thanks Warren. So no modification to the guide is necessary?
One more question that just came up: I have not yet removed the 3 part piston seal, my initial attempt at loosening the screw that holds the seals to the piston was unsuccessful. In looking at the parts diagram I see there is a pin shown at the head of the piston (Umarex p/n 300293), which could act as some kind of lock for the piston screw. I cannot locate this pin. Do I need to remove/pull off the outer piston seal first in order to uncover it? Anyone care to provide the disassembly sequence?