The principal components that are likely to wear and suffer long term damage are the selector forks.
When rebuilding the gearbox assembly however, where possible, replace the complete gear train, including this 2nd GEAR for a cleaner sharper gear shift.
Why not order all the gaskets you require at the same time - save money on shipping costs with a multiple order.
Try this gasket sealant: 08CRAHLG120G as used by the factory professionals!