DIY
-) With a fine rotary grinding blade and a sturdy hand one should be able to cut the teeth oneself out of a piece of steel or brass.
-) There are specials thread-files (not rotating taps) made to cut small dents at male threads, thus making the thread usable again. They are rectangular and hold 8 different tooth patterns to fit respective threads.
I guess one pattern might sufficiently fit your pinion gear.
In case, cut a piece of brass to size, fix it in a vise, with a piece of flat metal with rounded edges as a stop to one side. File the pattern into your piece of brass.
Otherwise any (fine-) mechanical workshop should have tools to cut sprockets.
Your pinion teeth hardly will match current industry standard anyway.