Dave
Usually it's the opposite problem - I.e the cap works loose over time (which is why, when I make a new cap up, I drill and tap to take a locking grub screw.? )
I think the hole is for lubrication purposes - to lubricate the rod which operates the rachet.
Only things I can think of are that the bush in the center of the tube has worked loose and is jamming things up or the small (8mm) screw which holds the pawl in the bottom of the lever has worked loose.
Either way it's a gearbox tunnel off job to see what's gone on!
Arwyn
