Carmine,
Having the CRT high voltage too low is the culprit when the picture is too large, the opposite to what you were thinking. The higher the acceleration potential in a CRT the more deflection power is required to deflect the e-beam the same amount, so lower high voltage means more deflection. That would also help explain the blooming. As to the crackle, well your voltage may be so low that it is below where the focus regulator can keep things level. I'm assuming you have a 6BK4 shunt regulator when I say this.
Make sure that the outer aquadag on the CRT bell has the grounding straps properly installed.
I cannot think of a simple and safe method of measuring the HV without a proper meter probe. It should jump About 3/4 of an inch to your finger, but that is only approximate.
NO DON'T DO THIS! I'M KIDDING.
That could knock you so hard on your ass you might never get up.