Wiper Problem

I just noticed today that there is a strange problem with my wiperson my 110 TD5.

On all setting excluding the fastest setting pushed to the top the wipers are working fine. The wipers stop and start at the correct point.

But when i push the stalk up to the top for the fastest setting the wiper just stops dead wherever it is on the windscreen.

Not the biggest problem because i nearly never use that setting on the wipers but still would like to fix it if there is a easy solution.

Thanks,
John.

problem with the wiring in the wiper stalk..
take apart and give all contacts a good clean

I saw something about a park switch? Could it be that or can it be just somthing to do with the switch in stalk?

Managed to find the problem.
I traced it back to a loose connection on the wiper motor.

All is working again.