white knight cl447wv tumble drier?

No heat from drier.
HI Lo switch on front was said to be at fault and was supposed to be changed by repair man - looks like the same old one to me. Checked continuity of switch and is OK.
Did find small red button on rear of machine - looked like a reset button - pressed it and now I have heat - is this a thermal cut out and if my machine was pushed too far back to the wall increasing the heat in the rear of the machine would this cause it to activate? Or do I have other probs?