Bosch dishwasher won't stop draining

Hi

I have a Bosch Classixx dishwasher - model SGS45C08GB/06.

I had a problem where the dishwasher wasn't draining properly - 'check water' light was showing. I lay the dishwasher on its back, removed the bottom cover and was able to unscrew the pump. Sure enough, I found some small pieces of plastic that were blocking the impeller. I removed them, and re-assembled.

Now the dishwasher drains fine (I filled it directly with about a litre of water), but it won't stop draining. I left it running on a long cycle and eventually became aware of a burning smell. So I stopped the cycle and removed the base again. It seems the smell was coming from a float switch (the one that sits directly above the polystyrene flood prevention float in the base) - part of the switch casing seems to have melted and when I unplugged it I found the contacts were blackened.

If I replace this float switch is this likely to solve the problem, or is the burned out switch likely just a symptom of something deeper and more expensive?

I've tried making sure the base is thoroughly dry inside (even used a hair dryer on it). Tried tipping the machine on its side, as per a tip I read on another forum. But no success. Wondered if the float switch has got wet, while I was cleaning the pump out (there was some spillage), and this has caused the switch to short out?

Any insights very gratefully received!

Thanks
Paul