All fixed now thanks to everyone’s advice, the thread was completely shot so ended up putting a stainless threaded bar straight through heat exchanger with a nut and washer either end better than original design 👍
Event everyone I’m after a bit of advice, I tried to take side plates of heat exchanger, took the through bolts of and the plate is solid, does it need a good wallop with mallet or is it threaded??
Fished of coral today some nice cod up to 9.5 lb loads of big blondes up to 20 lb and the usual dogs, when I came through lock gates nearly every boat had decent size cod to 12 lb haven’t seen so many cod in years tight lines