These heaters usually have a thermal fuse set in the mica side panels. They are colour coded, but temperature is normally written on the side. Easily replaced. 😉
if u get a hoover td with old thermal fuse must upgrade to new style with 2 stats on . hoover had problem with these models catching fire., also on w/m dated between 99 and 04 must replaced mains filter these also catch fire. although hoover will not afficaly comfirm this. im ex hvr so know it to be true.