Hi Gareth
I recently fixed the thermal fuse on my TV630, It is located on the inside of the heater element, It was a bit of a pain but it worked I got the part from Maplins, unfortunately it only lasted for 3 weeks and then all went cold again! I would advise you to just replace the Heater element as a whole as Hoover have brought out a redesigned heater for the TV630 with different thermostats, in twin configuration rather than the single thermal fuse. I only say do this because it is so much easier to fix, the heater is a doddle to change and I got one for £23 from ASD Services. It would also be safer than changing the fuse too, It is a bugger to get to and you would need a precision soldering iron.
What ever you decide, Good Luck
Let me know how you get on and/or If you need any more info, just post on here and I'll check it now and then.
Richard I, March 2008