Well that new soldering iron hand piece turned up and found the temp reading is not working properly but the max temp dial can still set the temp.

So with my big tip desoldered the mosfet and found the 12 volt 5 watt zener was toast so just on on and ordered a few more so this time I do have spares  

Regards Bryan

Anyway I found a quick fix as the black plastic nut was broken on my old handpiece I just swapped over the top section with the new top section and screwed it tight on, turned it back on and the LCD display is fixed.

Well those 12 volt 5 watt zeners diodes have turned up this morning so lets see if I can let some more magic smoke out today