I've been trying to remove 5th gear from my gearbox (Mk6 Fiesta IB5) for the last day with no luck. When I start to tighten the gear puller it slips off. Can anyone at all help???

I think the gear puller is supposed to go behind the actual gear but there isn't enough room so I'm putting the lugs on the front of the gear where the is a small ring/ledge.

Please help

Cheers
Ste

This is the gear puller I bought: