Although time consuming you can oil stone the spring down.
Knife sharpening stone....very fine
Like Larry stated above.....
It,s less aggressive does not involve overheating the spring and you can control the "tune" of the spring to your liking.
Dave being a bottle digger back to 80,s I always wished to find a squat ale like the one on the table although I never did.
My digging buddy found a early metallic cartridge inside an ale bottle.
We wondered what the conversation was that night with the consumers of that Ale!
true story!