Not hard to fix, I believe that Rich in Mich can sell you good, used Gamo springs. Or you can upgrade as I'm sure you're aware.
To disassemble it, you can follow the directions that CDT has on his website for the B19. Obviously, you don't have to go all the way if you don't want to.
Personally, I don't use a spring compressor and I ain't all that strong - but do so at your own risk. When I'm ready to knock the rear pin out to release the spring, I just place the barrel/compression tube assembly upright on a wood surface, press down with my left hand and push the pin out with my right. It has about 65-70lbs of preload and about 2" of compression.
Or, I'll punch out the pin with a phillips screwdriver or a punch that's smaller than the pin. After the pin is driven out, the punch or the screwdriver will now be holding everything together. Do the same thing as above, and slide out the punch when it's unloaded.
