Hi Thanks for replying, yes have Multi meter shall post pic of circuit board.
had tub approx 6 years used for 4 then decommissioned got back up and running to find all run ok but tripped a fuse the following day.
diagnosed to the element which had split, changed for 4 kw Titanium, all ok no tripping fuses will hold temp, currently at 32deg, but on all day not rising above that temp. Thanks.G