Replacing a broken drive belt on a Flymo Power Compact 330?

With the new belt located over the motor`s drive bobbin and over the fan/blade pulley it is a very slack fit. The adjustment slots on the motor housing are already at max adjustment and I cannot see how to tension the belt in order to give drive to the fan & blade. If the belt is fitted in a figure 8 configuration it could be adjusted to fit and be tensioned. However, this cannot be the way as the belt would be in contact with itself at the cross over point. I do have the correct belt. Any advice please.