Front sprocket output shaft seals should be replaced straight away as dirt and debri can enter easier here causing excessive wear to the shaft. Extensive damage to the shaft will mean that even a brand new seal will leak due to groves / pitting made in the area where the seal sits.

Worn Crankshaft seals on a 2 stroke engine will significantly decrease power output, depending on the seal in question they will either draw in air or gearbox oil into the engine so it is vital that these are replaced immediately.

Worn gear selector shaft seals dont pose that much risk to the shaft itself as it only moves when a gear is selected but if left for a long period of time the water, dirt and debri in that get past the seal, this results in this shaft being pitted and then when you you replace with a new seal it would still leak.Athena has the world's largest selection of shaft seals.