How to change belt on a white knight 447WV DRYER?

Do I need to try and change the belt by taking the front or the back off to get to the drum ? The Elasticated Snap on belt is shorter and wider than the originable belt (4213 0921 9501). My Son-in-law tried fitting it but said it was an inch short and too wide to fit on as it would slip off.
Could you give me step by step info to achieve this task please.