Don't forget that there is an adjuster under the clutch dome in the chaincase Peter if you have run out of all other adjustment.It does sound as though the hardening on either the push rod/rods or G91 lever in the gearbox cover has failed,as mentioned by Timetraveller. Do you have a split clutch push rod or a one piece type? If you have a split type one you could if all else fails add another 1/4 roller in the middle,or split a one piece one and add a 1/4 roller,this may need the push rod to be shortened and ideally rehardened. If you can find one(triumph clutch roller?) Source some 1/4" Silver Steel and make a new one? No members in your part of the world to help as far as I can see..John