Dermot
I assume that you have the correct belt - one with 5 Vee's in it. The belt goes around the main drum, then over (not under) the black jocky wheel and under the main drive spindel. If it is still loose (which mine was) you will need to check the spring on the side of the motor housing.
I have just changed the same drive belt in a TC-460 and the belt was too loose to start with.
Mine had a spring on the left hand side of the motor housing (between the motor and the chassie) which pulled the motor asembly down to the left and caused the belt to be loose. I unclipped the spring from the motor and moved it to the righthand side of the motor housing, this then pulled the motor to the right and applied enough tension so that the belt would run. I assume they have changed the size of the belt at some point and the replacements are longer than the originals by about 1 - 2 cm.
A word of caution, try not to remove the spring from the base of the motor housing as it's a real pain to get back in, and, if you need to raise the machine to work on it - remove the water collection tray inside :(
Good luck.
Jim
Jim, December 2004