Series 3 Wiper strange behaviour

Hello
My windshield wipers work well all the time except for when it rains. When I turn them on nothing happens for the first few minutes then slowly slowly it comes to life with very choppy and slow motion. 10 minutes later they are working as normal and then they start to pick up speed and work much faster than wiper should. Any idea why this is happening? As I mentioned this only happens when it is raining. In dry weather they are normal.
tx in adv

Brushes? Commutator? Binding?

sounds like something is either binding, clogging up the electrics or worn brushes.

Bobsticle said:

Brushes? Commutator? Binding?

sounds like something is either binding, clogging up the electrics or worn brushes.

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If this was the case, surely they would play up when it's not raining too. I'd be looking for water Ingres to the electrics.

Col

Col the strange thing is that after 15 minutes of driving while it is still raining the wipers start to come back to life and pick up speed. Surely water is a factor but it could not be evaporated during those 10-15 minutes. Question is where can it be that possibly heat will evaporate it in such a time?
Merry Christmas and happy new year (a much better year hopefully)

Happened to mine. Eventually motor died. Turned out it was just a buggered motor , original one, insides all full of crap. Replaced the whole thing, motor, wheelboxes etc.