Is there a ratio adapter on it now? Is it a 90-degree drive ratio adapter, or just a straight through? Do you know what ratio it is? Is it non-functional? Have you pulled the driven gear out to see what color it and the drive gear are? Yjos os pretty easy to do.
If you tell me the drive gear color (look in the hole with a flashlight), the driven gear color, and the ratio of the ratio adapter (for AC D0elco 90-degree adapters, it may be stamped on the side; for others, you can turn the driven side 10 turns with a screwdriver while counting the turns the output side makes), I can give you options, part numbers, and probably suppliers. I just went through all this.