Just for future reference, questions about pre-'99 Sprints belong in the
T3 forum.
The switch in question does go bad fairly frequently. It's located on the underside of the lever perch, & it's interchangeable with several Kawasaki models including the Ninja 250. ('87-'07, not sure if the new one this year uses the same switch.) Also, of course, interchangeable with any of the other Triumph 900 triples & 1200 fours from the same era.
2020154-T0301 is the Triumph part number & 27010-1170 is the Kawi p/n. Note that the retail price on the Kawi part is actually 71 cents higher than the Triumph.
Cheers, HTH,
-Kit