I'm sorry I don't remember what tip attatchment I used, but I did use a dremel. I struggled with an exacto knife for a while before I justified going to the store and buying a dremel

Likewise for me, no flashes in 4 months, and a TON more light.

EDIT: try using a very small tip at a high speed.

I just used an old soldering iron and melted 'em out. Now I have a set of sockets to put in there so I won't have to do that next time.