For the benefit of Google:

When the machine was turned on, all leds on the panel flash. Machine
then works normally most of the time but goes mad sometimes (spinning at
high speed and won't stop). Takes a power cycle to clear it.

Remove the rear low down access panel, and the diagnostic port cover,
and the screw below it. The control board lifts out and can be squeezed
past the motor. Note the cable locations!

One failed 680uF 10v electrolytic with visible bulging, so a few minutes
soldering and it's fine.