Mk 1 Yaris intermittant wipe not working

[talldave]

Hi all - the intermittant windscreen wipe on my 1999 1.0 petrol Mk1 Yaris has stopped working. Normal speed and fast speed both still work OK, but not intermittant. Also when I pull the stalk lever towards me to get the squirt onto the windsreen, the squit works but the wipers don't operate (i.e. I don't get the normal 2 or 3 wipes that I should).

Any ideas? Is this likely to be a fault in the stalk on the steering column or with the wiper motor itself? How does the intermittant wipe actually work? Is it a timer/rotating contact/heated expanding bimetalic strip?

Thanks in advance.