After far too long doing nothing with my 100E's dismantled engine, I did manage to get around to replacing the piston rings tonight. So far so good, but my curiosity was piqued by a couple of things.

1) I couldn't help but get a few scratches on the pistons as I was putting the new rings on. Is this going to be a problem? They're too shallow to be perceptible by touch, and the old side-valve isn't exactly what you'd call a precision engine, so I'm thinking not but thought I ought to check. When do a few scratches cross the line from acceptable to unacceptable?

2) The tops of the pistons have what seems to me like some fairly heavy pitting on them, which only became apparent once the oily layer had been scrubbed off. I was wondering, for one thing, how that would happen and, for another thing, if this is also a cause for concern?

I appreciate pictures might help so if anyone should want to see some then I'll go and take them.