Gear change shaft oil seal AP0250450
Fitment - RSV 98-10, Tuono 02-10, Falco 00-03, Futura 01-04, Caponord ETV 1000 01-07.
OEM Aprilia gear shaft oil seal, part number AP0250450, item number 24 in the diagram.
Over time these items can wear out just enough to allow a small amount of oil past them, thus a leak has formed. If left unattended the leak can become worse which may allow oil to not only contaminate your engine casing but worse get onto the exhaust or back tyre, both of which could be serious.
As its a part that will fit straight on, it can be done quite easily with great results.