Generally it is where the piston threads on the shaft and where the piston seats on the shaft.------( I will bet when the previous owner or shop changed the piston it was not sealed correctly )shift96 said:
Every once in awhile it is the "O" on the piston , or the "O" ring on the end cap, or even a schradder valve core .
I like to pressure test the cartridges under soapy water and see if I can detect any leaks anywhere,
Then I will inspect all the sealing areas , lube and replace "O" rings and reseal the piston with blue locktight and replace the schradder valve core .
p.s. If you get a fox 36, do not get a TALAS travel adjust fork.
I get more of these with way more problems that you could imagine.
The fixed travel 36 is not to bad , ---However I have one of those that has come appart after 2 months use :madman:
All these componets need to T.L.C. to get them perfect