Getting there. I still need to wait for the original piston to come back and then sort it out.
As I thought one stock screw had just broken into the wall of the transfer port, I tried to epoxy a bit of aerial into the the port but i think most of it came off as I was pushing the bit of aerial in. So i tried to put a bit of epoxy in the screw hole and put a screw in to try to persuade the epoxy to seal where it needed to seal. I then took the screw out and cleaned any residue off.
I put the gun together late afternoon and it still didn't always fire a pellet, which I think was partly the breech seal gripping the pellet and partly a grubby barrel (maybe the piston washer a bit tight too?) . Anyhow after good barrel clean and easing the breech seal it started to plink well. It is shooting a fraction high and left but grouping really well. I'll leave the sights until after I've refitted the original piston.
There is a slight kick to the gun, which might be either a tight piston washer, or the bit of aerial in the transfer port needing to come out--------even though the port still looks fairly big.
I don't think it is an under powered mainspring--as even though I'm not sure what it is, has a bit of pretension on it.

Has anyone ever tried to sleeve a Cadet port? I only really tried it to stop the air leak.