The bronze crankshaft gear drives the distributor shaft. If a gear is damaged, the distributor may spontaneously jump a few teeth or move from the original ignition timing.
Don't think you are an exception when you discover during overhaul that the gear is damaged, in the majority of engines that undergo a total overhaul it is necessary to replace this gear.
For disassembly you use a crankshaft pinion extractor (indicated in the options tab) and for assembly it is advisable to heat the pinion. This allows the gear to expand so that it is easier to slide it onto the crankshaft. If this is still difficult, you can put the crankshaft in the freezer for a while.
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