new clutch cable and the ball snapped off on the lever end on the first pull.
The nipple in the handlebar clutch lever should be cylindrical; if it's a "ball", is/was there a loose cylinder on the cable inner with an indent for the "ball"?
Nevertheless, if that really is a Barnett cable, not a fake, Big Black Mark.
When the handlebar lever-end nipple was a cylinder soldered to the cable inner, the inner was "bird caged" after threading through the nipple - the inner strands were separated for a short distance and then formed into a ball that fitted in the indent in the nipple. Then the wire-end 'ball' was filled with solder that both attached the nipple to the inner and prevented the 'ball' of wire and solder pulling out of the nipple.
fork in the gear box only has about 1/2" of motion up and down.
Will probably have less when the clutch is properly-adjusted. Having connected the next
new cable at the gearbox end, before connecting it to the handlebar lever:-
. Remove the adjuster plug from the primary chaincase.
. Loosen adjuster locknut and unscrew it a few threads on the adjuster, so it can't contact the clutch when you're adjusting.
. Initially, screw in the adjuster several turns; if you feel resistance change, so much the better; the idea is you want to be sure what Triumph termed the "Clutch operating rod" is definitely pushed up against the clutch actuating mechanism in the gearbox cover.
. Loosen the adjuster again, tighten it again but this time with the screwdriver held just between thumb and forefinger; reason is, if the screwdriver is held in the fist, it can be difficult to tell when the adjuster contacts the end of the "operating rod"; otoh, with screwdriver just between thumb-'n'-forefinger, it isn't possible to apply enough force to start compressing the clutch springs.
. Having set the adjuster accurately against the end of the Operating Rod, and knowing the other end of the Rod is against the clutch actuating mechanism, unscrew the adjuster between 1/4- and 1/2-turn, hold it in position with the screwdriver and tighten the adjuster locknut.
. Refit the adjuster plug in the chaincase.
Attach cable to handlebar lever and adjust for correct lever play.
Btw, if you haven't seen it posted before, my T100's clutch cable - long enough for US-market handlebars - has 48" outer including the ferrules, 51.5" inner including both nipples.