Miele G1242 SC not doing much

Regardless of selected program, the upper of the two valves near the heat exchanger (I think it’s the fill valve) buzzes quite loudly as if it’s not properly energising. It does this for about ten seconds, then nothing, then buzzes again. I tried disconnecting power to it and then the drain pump kicks in instead. Probably not related but I noticed that the terminals to the adjacent valve (regeneration?) seem a bit corroded. Customer reported that it was displaying ’18’ although I think this may have been the rapid cycle duration.

Any pointers gratefully received,

Derek