IT literally means that the piston and the sleeve have rubbed against each other for too long and that there is way too much gap between them at this point. this lets the expanding gases LEAK through this gap and this means loss of power!

you can replace it or get it "pinched".

The philospphy is that since its just a tad loose, who not just crush it back in?!
I dont know how it works but I think otheres can give you some info on that.
Also search a few previous posts I think there are some numbers to call too on some of the older posts
-ram