zanussi zwf1637 behaves for 20mins and then motor goes nuts

basically as above. 2007 zanussi zwf1637 with the flat button-type control panel, and skip option

put it on for a wash, delicate, agitages perfectly normally for 22 mins then the motor tries almost to spin itselft up to a high rpm, it does this twice then doesnt abort, it just sits there and does absolutely FA for as long as you want to leave it (i got bored after 5 mins)

anyways, i paused it and then tried the skip option to spin it and it wouldnt have it, so cleared the programme by skipping to end.

then put it on cottons and before starting, skipped it through to spin and it tried to do the mega spin two times, whilst draining. and then cut out but with already lit leds still alight.

cleared it and started it again on spin, same thing

cleared it and did it once more and it spun fine – even allowing it to drain first before actuating the motor.

anyway
ran it through the spin, wondered if water level was an issue, so put it on a full rinse. ran that for about 4 minutes, then skipped it to the spin and it worked fine again.

Its very odd, had the tacho off and it all looks fine, and reads ok on multimeter, brushes were 1/2″ long, and main pcb looked fine too. no pump blockage and pump impellor didnt seem impaired.wash element seems ok, and it passed loads of diagnostic tests. I did get e52 before i started looking at it, and e52 after teh nutty motor bit, but if it was the tacho i wouldnt have expected it to wash fine for the first 20 mins, or pass diagnostics? any ideas before i presume its the pcb ?

oh and the acc/sole motor seems to get much more noticeabnly warm quickly than other machines