You can always take it down, open up and see which gear is broken, then have another one made as per sample by an engineering company ( or if you are lucky it will be a standard gear available off the shelf at an industrial parts supplier), then replace the switches and the upper seal, and when installing the new switches use a generous coating of light lithium high temperature grease ( not silicone based though, they will cause you grief) all around the switches and the terminals to keep them dry.
Phoned an industrial company this week, to ask them about some equipment we have. Spoke to the guy who made it, and he was able to tell me when it was made, 1975, and the specs I wanted. They still have the drawings for it, so if I have to get the spares that they fabricate I still can, at a price. Will still have to get it assembled on site by a coded welder....... The control gear though is all no longer as supplied, I went a long time ago to a soft start control ( expensive at 7.5 kW rating) and replaced all the star delta switching ( original idiot installed it to start in delta and switch to star, and it eventually dropped a phase on the one contactor and burnt out the original 130kg cast iron monster motor) to get a gentle starting so it did not want to pull the mountings out of the floor. Just have to replace a weeping gearbox seal this month, easy enough as it is 4 inches in diameter.