MSD gone bad?

[pishta]

I got an MSD 6 and it looks to be only sparking once at idle. Do these go bad? I used the same timing light my friend used on his 6-AL and we saw 6 distinct timing marks on his damper at idle. He had an MSD distributor, and I have a Mopar electronic tach drive model. Also, the tach out doesnt want to fire my Sun Super Tach II. The book says it should. Thanks