Philco 38-4 questions

[Electronic M]

I have a 1932 cathedral that as found (all original except for the 40's lytics tacked in parallel with the originals) 2-3 years ago ran on it's original caps...Albeit with weak reception and audio distortion. It used all block caps for it's paper types. Re-stuffing the blocks brought it back to being a strong performer.

I don't own a heat gun, and have not encountered a block with one of the harder potting materials that, I seem to recall reading, were made so the chipping method is the easiest means at my disposal....The tar is so soft a little bit of pressure will sink the blade of a flathead screwdriver a surprising distance into it...

[darklife]

All the wax capacitors are now replaced along with the ones inside the bakelite blocks.
Found a 3.5k resistor that was going bad and overheating in the audio section which was causing the popping sound. Replaced with a higher wattage value and fixed that right up!

Radio sounds great now except that I am still having two problems:

When I turn the volume up past a point there is a crackling sound from the speaker. Sounds like real bad distortion and is sudden.
I wonder if this could be the speaker itself? I noticed before that when moving the voice coil by hand that it sounded like it would rub sometimes but wasn't sure if that was just from me manually moving it or if it does have a problem. If so is there an easy fix if that is the cause?

Other problem may have to do with the 6F6 tubes. With a few different tubes the radio can go from sounding good to sounding like there is motorboating or some kind of feedback with the volume all the way down, or up.

Reception has improved greatly after recapping and a tuneup but I still think it should pick up more stations on SW and not need such a long antenna on MW. Maybe I am expecting too much out of such a simple design
The wall voltage also worries me. How do these old sets fare on modern AC wall voltage? I think our voltage runs close to 125v here.