This is for the 'First edition' TDL11P dryer but probably similar for others.
First - be sure it is the belt. If the dryer is operating correctly but the drum not rotating, then it probably is. Look at the back and see if the fan is spinning. If it is, and the dryer is not rotating, then the belt must be broken or off.
Next - order the belt. There aint no point dismantling the thing before you get it.
Third - prepare for action. REMOVE PLUG FROM MAINS. ENSURE SAFE ISOLATION. Then move the thing to a good clear patch of floor, and get a good vacuum cleaner ready! It's a good idea (I Think) to vacuum all the fluff out as you go. You'll also need a cross head screwdriver, preferably mounted in an electric screwdriver.
Fourth - start taking the thing to bits. This is an explanation of my way of doing it which was found by trial and error.
Now, heres the thing - the belt (obviously) goes round the drum about midway along. To get the belt on you'll need to take the front off, but bear in mind you can't remove the front far, due to the wiring to the door switch and the loom run along the bottom.
So, take off the top, 2 screws at the back. Remove the control panel front - remove two screws from INSIDE LHS (as you look at it from the front) and gently pull away the left hand side of the panel. Ease it to the right, and it will clear the lugs over which the right side is clipped. I found the dial knob popped off all on its own....
Remove bottom trim panel (no screws). Lie machine on it's back. undo complete centre front, three screws top, same bottom. GENTLY move the front panel so that you get working room. take out plastic vent tube - it'll go back in from the back later. Hoover out the interior. Ease in belt so it goes around drum. Replace front. Move machine to upright position and just check drum is still rotating freely.
From the rear, remove two screws from vent housing thingy (the bit at the rear to which the vent pipe attaches). Stick arm in, feel to your left for the motor spindle. Grab belt, put it over motor spindle. You may need someone to rotate the drum for you at this point to help things along. Once done, rotate drum while looking down to ensure belt is tracking straight in the right position - previous wear should have left witness marks on the drum, so that should help you. Make sure drum revolves smoothly.
Stick in plastic tube previously removed. Replace vent housing thingy. Replace top. Check no bits left over :) Finished!
C_Steam, January 2009