Hot water system sometimes not working, main switch on circuit board is very old fashioned and gets very hot when on even though it is not heating the water, fuse OK. Rest of main switches modern
System bled apprears OK

I would get a electrician in to check out your fuse box and check the elements to see how many amps they're pulling. Let me know what he says. Don't let this slide. Something's very wrong if the main switch is hot. Good luck, Tom