I don't think there is a parts number for this item
This is the link where you can see the product
The bottom section lifts off from the handle so a blower or vacuum can be attached.
Each section has 2 plastic tabs designed to sit inside a recess and depress a switch which enables the fan to work. If the blower or vacuum are not attached a safety switch then disables the on/off switch
The tabs are complete on the blower but have been broken on the vacuum section which is disabling its operation totally