gear box

hi all the clutch lever assy at the rear of the gearbox when removed has wat guzzi call a outer cover with a oring fitted you remove this cover to change the thrust bearing if this oring is damaged will it leak gearbox oil

Yes , that’s what it is there for to stop oil leaking.
Available from gutsibits for not much, delivery service excellent.

when you take the clutch lever of the gearbox does the cover / outer body just pull out to get at the oring and can you do it without removing the gearbox from the bike thanks

If it’s lke the big blocks the O ring(s) is/are in grooves of the actual clutch thrust piece, so should come out with it when it is removed. No need to remove cover. (But as I say IF…)