my creda t601cw doesnt dry clothes, i have changed thermostats and heater?

hello, please help, i have a creda advance t601cw, i have had it about 5 years without problem and always kept it clean. last week it stopped drying - on closer inspection it wasnt getting warm, i checked these sites who seem to recommend changing heater element / thermostats - i purchased both for about £40 and installed them fairly easily, however the tumble dryer still doesnt appear to heat very warm, , please can anyone help?? i have heard it may have a 3rd thermostat? i cant seem to find a diagram anywhere online, please reply ASAP as my radiators are chocka block, thanks in advance for any help :-)