Also, the bottom center is adjustable with a screwdriver. You might try screwing it in just a tad. It becomes a balancing act to have it low enough to make contact with your mod but not so low as to lose contact with the head. I also like to just tighten every thing firm but not super tight.
It's also possibility that you had a short that was keeping your pv from firing, and you cleared it when pulling out the center pin a little. I recommend not using nail clippers or scissors to trim the wire. Just rock it back and forth until it snaps flush.
On a similar note, make sure that your wire doesn't get pushed back inside when you put the pin in. It could hit the walls and short.