White Knight tumble dryer Model No. CL 447 WV?

hi all , my problem is that my dryer has just had a new thermostat fitted and now it is not running as it should it is getting hot as it should and going around but not in the manner it was before it keeps stopping and not going in reverse as before the outer drum seems to be going around as it should but the inner drum is not and the clothes are all sat in the bottom of the drum not going anywhere ???? this keeps happening ....all help in this manner is very much appreciated ,thanks