tumble dryer not drying very well?

got a whiteknight tumble dryer, been fine for many a year but latly its taking 2 sessions to dry stuff, its got high and gentle heat options and is always on high but its almost like its on perminent gentle, if this is to do with the heating element then wouldnt it stop heating altogether? and its started to squeek, ive heard somthing about a copper strip, where can i get this replacement bit from?