>>9152806>replace the pegsThis is assuming that you can't retrieve the stuck peg intact. You'll need either cut out a rod from the runner (if the diameter is right) or buy stock styrene extrusions. Tamiya, WAVE, Evergreen are some of the hobby companies that make these.
>pinningDrill a hole and put a metal pin through the peg then glue it. It's for reinforcing the glued joint so it doesn't just snap again. Your peg seems to already have a hole so you could use that if you find a matching diameter pin.