simply, the unit on my 1991 250 is damaged. no spark on one cylinder. sometimes when I tap it gently, starts working for a short period of time. I already checked connections, and unfortunately only after replacing affected coil, I tapped the igniter and discovered the the issue.
Since old ones are hard to find, I was thinking of using newer one with different # of pins ( socket size looks the same) .
Also they don't last forever. 6 months ago I replaced one with similar problem, however, affecting both cylinders