Again this is a very belated reply, but might still help someone. See long description on thread about a ZWF1640W Zanussi washing machine, which looks like the one picture you post internally and how you describe it. This had exactly the fault you describe, with an intermittent refusal to start for many years, plus I also noticed a tendency not to run two washes one immediately after the other, but worked better if i waited a bit.
You first say the error was E34, then later E35. Assuming it was E34 this means inconsistency between the analog and mechanical pressure sensor. In your pic there are two tubes coming off the drum from the bell pressure chamber, one goes to each.
The step which fixed my machine was to enter the service menu, exit the menu by moving to the power off position, then switch on again to any setting. This starts a different process which I have not seen described in any of the service manuals i have found online. The display showed ELE I think. The service descriptions didn't explain this, merely said that once you reach this step immediately switch it off again and then it would work normally next time turned on. However, I let this run, it filled the drum to normal wash level, maybe did a little splash, pumped out and then stopped. After that i switched it off, then back to a wash cycle and it worked normally.
I suspect this runs a calibration cycle between the analog and mechanical pressure sensors. I suspect that because some info about other brands of washing machines talks about calibrating the analog sensor, and it makes sense how the hardware could be OK but the machine not be working, or having an intermittent problem.
Before I got to this stage i had already replaced the analog sensor and checked the mechanical one which seemed to work fine. By itself this didn't fix the problem, until I did the cycle as above. Since i had a new sensor anyway I didnt switch back to the old one, but its possible the old one was working fine but somehow its calibration has drifted over time so that it was first sometime out of range and then permanently out of range. So its possible just doing the calibration run would have fixed it without even having to open the machine. Or it could have genuinely failed.
While investigating all this I found the circuit board was completely covered in black dust, which I think was ground up carbon brush dust from the motor. I cleaned this off because it didn't seem likely it was helping, but by itself this didn't fix anything.
Oh, there are a whole lot of different models and different name machines which are very similar internally to this one. Hotpoint EWM2000evo motherboard. Note though different models may use different software programming on the same board.
