Having some intermittent problems with my 124 wipers (no pun intended!)

On one car, the wiper sometimes switches itself on for no reason, or occasionally when the turn signal is used. It only stops when the control is turned to full on, then off again.

On the other, when using the intermittent switch, sometimes the wiper sweeps continually as if it is in position 1.

I realise this is most likely due to bad connections in the switch, so what I'd like to know is whether its possible to strip the switch arm down for cleaning, and if so, where would I start?

Or is this a problem due to a faulty relay, in which case can it be cleaned or should it be replaced?

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1987 300e manual 250,000 km (sold)