Intermittent door fault from ZWH7122J

Hi, have been through the forum / FAQ and can't find much that matches this issue. hope you can help.

Have a very frustrating fault with my washer - it's c. 7 years old, which seems young to me. Bearings recently failed and I replaced these with (I thought) no issues. Machine ran OK for a week or so, and then had door fail to lock which resulted in a cycle stopping half way full of water.

Replaced the door lock. It then worked fine for another week or so, before failing in the same way - it only seems to fail on larger load (eg sheets or nappies) which suggests its an overload issue? Happens during the wash part of the cycle, but has no issues with a fast spin. The interlock fail can be reset by turning everything off and leaving for a few hours, or disconnecting and reconnecting the interlock module. It doesn't display any error codes, just stops running (but also continues to count down).

Dilemma is that if I have to replace the PCB, it's probably not cost effective, as other parts are going to be getting towards end of life and PCB is over £100.

Question is - is anything else causing this? Does the door interlock contact carry the full running current? Or just a logic signal? Could I have inadvertently overloaded the PCB/door interlock circuitry by not seating the new bearings properly? I've compared the old door interlock with the new one on a meter and they're similar on continuity tests, just a slight difference in Ohms on the coil / bimetallic strip, so I'm not even sure if the old one had failed or not.

Is there anything else that could cause the washer to shut down part way through, and the door lock to then not engage for a few hrs?

Very keen not to write off a machine that (normally) works absolutely fine. but equally having to dig soaking laundry out of murky water every few days isnt fun.

thank you for your help!