Does this dizzy look good?

[dom14]

Hey guys,

This dizzy was running on my RB30 Patrol for a while.
It is the spare one, but I had it on for a while.
Basically I put it to test it months ago and then forgot

I pulled it out to have a look 'cos the vacuum advance appeared not responding.
(pulling the vacuum line out of the vacuum advance diaphragm seemed to have no effect on idling rpm,
so I suspected a blown vacuum diaphragm).

Upon opening it up, below is what I've discovered. The rotor & dizzy cap is covered with whitish kinda crud.

What caused it? Blown vacuum diaphragm?
Is it 'cos excessive carbon buildup inside the cylinders?
Or is it 'cos of bad ignition & timing(which also can be from carbon buildup?)??!!
Any thoughts, advice?

Thanx