How can i fix my Black and decker gw250 garden vac?

I broke the catch which holds the two parts of the vac together. I have bought a replacement catch, however when i screw the two parts of the casing back together it wont work. When i look at the part of the mechanism which activates the switch it seems to have a lot of play in it and doesnt seem to make the part travel enough to engage the switch to turn the motor on.