I have/had a similar problem. The little door that holds in the powerball tablet does not open during the wash. I got around it (temp fix) by dropping the tablet onto the floor of the washer, then starting the cycle and that worked OK.
I found that 'exercising' (ie forcing) the little doors catch to rotate (as it would when auto opened during the wash) seemed to free up something after it clicked and now it works.
Our models may not be the same, so maybe not exactly same problem - but I'm betting that if your tablet is stuck in the dispenser at the end of the wash, then perhaps its a similar issue - that the tablet is not being 'ejected' into the machine. So it could be the dispenser door not working.
My machine also recommends to use powder or liquid cleaner on Eco cycle BTW. Says eco is not hot or long enough cycle to fully dissolve a tablet. But then you say it's been OK before now. Could be a little part of the problem too?
kind regards. Tony.
tony h, October 2007