I also have a Warhammer Fantasy Army of Lizardmen. I will post pictures of them later. However, they have had a rough life and several of the pieces have broken, especially the stinking little flying bases (grumble, grumble, grumble). This particular model broke with the peg still in the Terradon's underbelly.
So I finally asked at my local gaming store, Albright's how to fix them and the guys clued me in. I filed off the rest of the peg to give myself a flat surface. I took a pin vise (rather than my Dremal tool) and drilled a whole down into the clear support peg, the exact diameter of the pin I would use. I made sure the well was deep, as I do not intend to glue the pin in.
Next, I took my Dremal tool and drilled into the peg still in the underbelly. Turns out, the guys were right to tell me to use a pin vise on the plastic. The clear plastic melted to the drill. I had to pry the stuff off. Once the plastic was out of the underbelly, I could use my Dremal to sink a nice whole. I measured and cut the pin and super glued it in.
The idea here is to leave the base free from the model. The pin is long enough that it will stay in during games but you can also remove the base for traveling. I have more Terradons to convert later but for now, they are still together.