Help tuning old Merc
 

Helping a friend with a 1969 Merc 1000. 100 HP. It has a Thunderbolt
ignition system. I pulled the distributor cap off and found why it
wouldn't start. The center post was broken. I'm talking about the
piece of graphite that transfers current from the coil to the rotor.
Anyway, what would shatter this piece? Is it indicitive of other
problems? Also, how do you remove the rotor? It doesn't slip off like
a car. Do I have to remove a larger assembly and how difficult is it.
Enough questions for now.

Scott