I really wouldn’t worry about it the bore is stainless, any marks won’t affect anything at all. If the piston was twisting you would see it from the bottom. Holes are for water entry.
There’s no way to see whatever you want to see at the factory, they would look same way as you.
If you ever need a new stainless liner, which you won’t, you can buy one. Never heard of one being bought yet.The problem seems to be a few groups leaking past the pressure seal I’ve told Paolo, he doesn’t know why, it’s a new thing as he has not had these problems before. He is in contact with the group manufacturers, trying to find out if anything component wise has changed. For which he relies on their record keeping or honesty.
It could be (as I think I might have said) a tension issue of the piston to splay out the pressure seal enough. This can be for multiple reasons, which need to be eliminated. Or it could be as simple as it needs to be tightened more….but not too much, or it could be at it’s limit.or, or, or
Or a change in supplier of that pressure seal.
People worrying and posting for more info, do they have a problem, what about this mark etc. simply take Paolos focus away from machines with a problem, especially with English not being his first language.
If people who get the problem and start doing things before they contact ACS they may be sweeping away any footprints in the sand. This makes identifying any issue extremely difficult.
I am frightened to even give my thoughts/speculation now as it starts a whole load of questions from people. If your machine works, enjoy it, don’t worry about problems you don’t have.
God help Paolo if he is trying to make sense of this thread now.