Thanks Cruiserman, gave your idea a try this morning and as I suspected only one of the three magnets was working.
I tidied up one of the other MOSFET's and scraped some crap from around it on the board and got another working.
The third one tho after messing around for ages I ended up having to run wires from all three legs of the MOSFET, looks like shite but it finally works too. I'm guessing there are broken tracks running from it.
I haven't seen anyone that sells replacement boards for this that I know off? Obviously mines working fine now but was just wondering for future reference.