sounds like the soap cam has stripped, remove the timer knob with a pair of pliers it may well break but since you cant lock it to disengage its a bit unavoidable. remove the seven mm securing nut from the centre of the dial and lift the knob clear. Remove the lid and the soap box. remove panel screws from lhs and rhs and the screws from inside the soap box. Along the rear of the panel you'll find a few plastic clips holding the panel onto the inner frame release these and the panel will lift off. Turn the timer by hand until you can see the two timer retaining screws, using a magnetic driver remove these and push the timer clear of the plastic cam . remove the cam and replace. rebuild the panel and fit the knob.
jim
November 2007