Spring & tune up

[Paulhaul]

Wondering if any of you guys can point me in the right direction. After digging out my 27 year old TX200 mk2 .22, I've just done a chrono and it's way under power (provided I'm using the chrono correctly)

I'm thinking that I should replace the spring and drop in a tune up kit. Is there any advice you can offer me as to what spring/kit I should be looking for?

Thanks,

Paul

[pelletcaster]

Concerning spring and other spare parts please have a look at the owner of this forum.
https://www.airarmsspares.com/air-arms-spares/

For tuning kits have a look here.
http://www.airrifletuning.com/

BTW - not using such a nice airgun for such a long time is clearly a sin .
There is a chance that the spring is still fine so just check the piston seal and breech seals and do a internal clean up and relube. Then chrony again.