Must be my week for machines busting, first my drill (now fixed), now
my washing machine, good job I don't have a pacemaker.

Washing machine is a Hoover New Wave+ 1500 (1996 vintage, actual model
is AC184)

Runs fine up until it starts to drain - drain pump starts and runs,
water is being pumped out, then it goes to a fault code (E1) and stops.

I've had the pump out, tested it, seen it runs, checked the sump &
drainage pipes are unblocked.

It looks like the behaviour I've seen previously when the pump has
something trapped in it - but this time it hasn't - and is (partially)
draining before going to the fault mode.

Any ideas?