I started with the main terminals on the thermo switch, resoldered them making sure to get a good contact to the curcuit board.
Then moved to the main curcuit board on the pbc resoldered any points that looked suspect, about thirty in all.
Re-installed it. Total job time about 35 minutes taking it slow and easy.
And Hey Presto. It worked beautifully.
Thanks everyone my most annoying problem gone.