Windscreen wipers

My wiper switch has two speeds which both work fine by pushing the switch upwards through two positions which gives me normal and fast speeds. When i push the switch downwards, it automatically returns to it's position, but nothing happens. I presume this is a one wipe function but this is my first landy, so i don't actually know. So, my two questions are - is this a one wipe function and if so, is it likely to be the switch itself or possibly a brush problem in the motor ?
It's in a 110 from 1990.
Many thanks.

Welcome to the forum, yes it's a single wipe and I would have thought that if it were a problem with your motor it would happen all the time.

Thanks Marmaduke, good to be here. I think the switch is the best place to start, i just wondered about the three brushes in the motor and maybe one controls the single wipe.

I'll be honest I've never taken one apart, might get a better response asking in the defender section

Ah, didn't know there was a defender section. Cheers.