As I was brushing my teeth at the head sink this morning, I happened to look out of the port above and saw that one securing (flange) screw had worked itself about half of the way out. I went around the boat and looked at the other three ports and found most screws were tight, but some a good half+ turns loose. Tightened all, of course being careful not to overtighten any. Guess that 37 years of vibration would do this. (Amazing I never had a leak but probably the sealing compound is still ok.) Wonder if a bunch of loose ones might eventually bring a leak, so am just relating my experience if others might want to check. Boats twist a lot under way, so probably having these babies snugged up is a good idea.