Hello Brock. I just used a small sharp knife to remove the trim, cutting into the glue and then (gently) prising the trim away with it. The glue let go quite easily after that on the straight runs but was very stubborn on the corners around the aft face of the keel box, which had to be freed a tiny bit at a time.
I haven't checked the condition of the cable yet but I suspect it'll be corroded after all that time (the end wasn't sealed). I might well replace it by soldering on a new length and pulling it through.
I saw your post on the P21 forum; it sounds like you'll find the end of a coax cable there too. Good luck!
Anthony Russell
235/02 Sea Wyche
Anthony Russell
235/02 Sea Wyche