I worked on my Fireball Classic the other night, Found it was going from Primary coil to the hold coil too soon. As the flipper travels through it's stroke, it gets to the End Of Stroke and opens the primary coil and holds with the secondary.
Some slight tweaking of the blade switch allowed it to have primary power until the last 20% of the stroke, where it opens the primary contacts. Before starting it was opening up after only about 40 percent of travel.
Now it's like a rocket.
I did also touch up the flipper button switches with a dull point file, as well as replace one of the blade switches on the flipper that had burned through and there was nothing left of the slight ball of metal making up the contact, but this was secondary to the travel, and switch opening issue.

Take a close look at the flipper travel with the power off, and by hand push it through its cycle from the bottom observing the cycle. You should see if yours is set up for holding the primary a long time in the cycle.
To everyone. If there is some reason this is bad please let me know.