Hello - I had the same problem a while ago and spoke with Aqualisa. It required a new dual speed assembly loom. I purchased this direct and fitted the replacement myself. Not sure about the blackness around the pupm - I had the thermo shower unit - details here http://www.aqualisa.co.uk/parts-store/Controls/Aquastream-Thermo-thermostatic-integral-power-shower/
David S
February 2008