Power started cutting out and then stopped completely

KMC510 model.
Been to the local Repair Cafe and they replaced the PCB KW37865 unit with a new one I had ordered as this was the suspected source of the issue. But it didn't work.
So where else might the problem be? I don't think it's the motor itself as it as working fine and the fact that it started as an intermittent problem makes me think that it's a connection somewhere that has finally gone.
I have been searching for a schematic for the mixer to see what else might be a likely culprit, but to no avail.
Has anyone had a similar problem with a Kenwood Chef mixer and what was the fix? I'm loathed to buy more spare parts as they'll just be stabs in the dark.