Thank you for your reply, god knows where the micro switch came from but where I found it there was a few dead fuses with it so maybe it's been replaced an just left in there (I hope) I'm gonna replace the pcb 1st then from what I've read and own (limited) knowledge!!
Hello, recently moved into my first house so all this is new to me, I have power to the boiler but no led indicators on front I tested the fuse and it's fine when I opened up the boiler I found this laying in behind the pcb which has thrown me