Thanks to all for all the help - but here is the latest...
OK, thanks to Little League tournaments (that is field setup and administration stuff) removing any extra breathing time, this weekend we took a break so I finally have a few minutes to have some fun...
I have it torn down. The rings wouldn't require a ring compressor if I wanted to put it back in because they appear to be glued into the grooves!
Seems like a pretty obvious issue that would definitely cause a lack of compression but wondering two things - first what probably caused it and second how the ???? do I get the rings out now without damaging the piston!
Basically think the reason for low compression is that the rings are stuck deep in the piston grooves! Doesn't appear to have any scoring and what little carbon deposits came off pretty easily - even with just a paper towel!
Have it soaking right now in gas to hopefully loosen up the deposits but WOW!
and of course the follow-up - heard locally that rings are about $13 a piece - is that reasonable? For the piston and rings I'd be looking at $150??
Do those figures sound right or should I be considering aftermarket? Or is that a 4 letter word?
Thanks