hoover vhc391-80

I have this machine that is haunting me :eeek: I have been to look at it a couple of times but the problem never occurs when I am there :rolls:

Basically the machine will run ok for a load or two, but now and again it will run for a short while then stop flashing empty water container and check fluff filter, whilst beeping.
Needless to say the water container is not full and the filter is clear also.

My customer then sets the machine on a different program and it will work again for about 20 mins or so.

When I called around yesterday she ran the machine and everything was working fine for a good 40 minutes, convinced it was again not going to show its fault she pressed the Acrylics/Synthetics option button and the machine stopped and began beeping and flashing the check water and check filter lights.

I am really not very familiar with these machines but I suspect it may be the moisture sensor, anybody else have any ideas?

I would normally point her to the manufacturer, but she is a neighbour so I need to either sort this or move house 😳

Cheers