[KTL]

Carefully cut the teeth off with a cutoff wheel. When you get close to deep enough, open the cut the rest of the way with a cold blunt chisel. Do at least a few cuts. The ring is an interference/press fit on the gear nubs, so it should pop apart when you give it a good strike with the chisel, so long as you've weakened the ring enough with the cuts to make it break

To install the new dog teeth, heat the teeth in a toaster oven (300F) and cool the gear in the freezer for several hours to ensure it shrinks as much as reasonably possible. The teeth will drop right on to the gear. Have something handy to pop the ring a few times if it doesn't drop all the way flush with the gear. A rubber mallet works good.

The gear and teeth will rust almost instantly. So have some WD40 or whatever handy to coat the gear after it's cooled off for a few minutes.