This post is on behalf of my Father (88). The question is in order to access the gearbox, can he slide the cover ( as shown ) straight off the shafts or does he have to dismantle the entire gearbox from the other side?
yes
he can access the gearbox when the inner cover is removed, he wont be able to remove the mainshaft as its still attached via the drive sprocket and clutch.
;)
Many thanks