Diplomat ADP8132

Hi,
I have an integrated Diplomat ADP8132. Last week it started to smell of burning plastic and then tripped our RCD. I partially dismantled it to see if I could see any obvious reason. The main board shows some scorching below a large zener diode (1N 5359B) near the large capacitors. There was some carbon on the sheath of the white cable spade connector which attaches to the main board nearby (one of the only 2 connectors which are on spade connectors rather than plugs and I assume this is the mains in). There’s also some evidence of melting(?) round the mains connector block underneath. Once the RCD was reset, the dishwasher remained partially full of water but didn’t retrip the RCD when it was plugged back in.
Having read various threads here related to this machine and more generic issues, I decided to try running it again. I set it to a strong wash and let it run. After ~ 30mins, there was a pop, a small amount of smoke and the return of the burning smell and the RCD was again tripped. I immediately took the front panel off the door to see if I could trace the smoke or the smell. It doesn’t seem like it has come from the main board. The smell was strongest down near the soap dispenser but there was no sign of scorching and it may be that the smoke has risen from the base of the machine and left an odour round the dispenser.
From my reading here, I thought that water might be dripping below the door as there was some evidence of drip marks there but it was dry when running just now.
I have thought of replacing the mains block but as they’re quite pricey, require a torx security bit and I have no idea why there’s a problem there; I thought that I’d ask for some advice here first.
Any idea what the problem is likely to be?
WHat other tests can I don in order to isolate the problem.
Thanks in advance for your help.
Regards

Seascape12