Early this summer I was heading out of the marina and a plug fouled. took them out and found one had no gap at all, (it was running fine before that) we thought that maybe a big piece of carbon broke loose or something. Re-gapped it and it ran fine all summer. Before putting it away for winter I decided to test the compression, that cylinder had 105lbs., the others had 110, 115 and 120. the manual says that it should not have a difference of more than 5 lbs. Other people have told me carbon would not have done that. I used engine tuner to clean it out. It seems to run fine, hate to tear it down when it runs fine but I don't want it to blow up on me when fishing or crabbing with grandkids either. Has anybody heard of this before and is there any reason for me to be worried? I would think if a ring broke it would take out some piston too, and run worse than it does. I put a lot miles on it since the plug incident. ANY IDEAS?