Re: thx russ, once again your info

Tom,

I understand that in Spain and other countries, people have been retrofitting the Gamo Shadow spring into the Norica Marvic which this gun is based on. Based on my measurements and testing, it would be a tight fit but I think with a bit of work it could be done. Based on my measurements, it looks like some of the seals that JM carries could be fitted to this gun. I have put together a dimensional drawing that covers the piston seal, piston, and front spring guide which should help with retrofits.

If you aren't into breaking new ground, you could try Compasseco and Umarex US for parts. Both have indicated that they would stock some but I haven't checked lately.
Compasseco sells the TF89 and Umarex sells the Hammerli Titan both of which use the same internals.

Russ S.