Indesit WD12S spinning dial and flashing LED?

My Indesit WD12S stops at random points during a wash and starts to spin the dial. it can happen during the initial wash, or during the rinse, although doesn't seem to happen during the spin.

The dial clicks round endlessly and the LED flashes 13 times. I read that this indicates a drier fault, but the drier component of the machine isn't in use, or set to be used after the wash. And when I do use it, it seems to work fine.

I've tried cleaning the filter at the lower bottom right (clean as a whistle), and checking the drainage hose (to the best of my ability). I had a look inside the machine and nothing seems to be burned out. I also did the "reset" trick by switching the dial to off, and turning it on. This initially seemed to work because a few washes went through inhindered. But the problem came back.

"Quick" washes on the number 8 program seem to work fine.

It MIGHT be the case that the dial starts to click around when the machine starts to drain, but I'm not sure.

Any help appreciated.