Since you suspect water intrusion, inspect other bearings for signs of wear or corrosion. It's wise to replace any questionable bearings while the gearbox is accessible. Replace the chaincase cover gaskets with high-quality parts to prevent future leaks and water damage. Consider using this...
Changing the bearings in the primary cluster sprocket can be a complex task, and the difficulty will depend on the specific motorcycle you're working on. But it can also be easy if you have experience.🥹:ninja:
Once the gearbox is removed and the chain (if necessary) is detached, you can replace the damaged bearing. Ensure you have the correct replacement bearing based on your Bobcat model and year.