I've replaced the seals in my transmission cover twice now, and after maybe 5-10,000km they seem to regularly fail again. One's a clutch pushrod seal, the other's the countershaft seal. I can't tell which is failing, all I know is that oil gets through into the area under the sprocket cover and the bugger ends up dripping oil, which shits me, because it's not even British. I wouldn't mind if they were easier seals to replace, but you've really got to cut the chain to get to them without munting a gasket. I'm gonna replace the f*ckers again soon - any ideas on how to stop it from happening again? Sand down the pushrod and the countershaft? Why do these things usually fail, and how long is it reasonable to expect them to last?