Sounds like the resonance is too high... just as a simple experiment, try the coin on the headshell trick...
Perhaps you are heading in the wrong direction for that stylus! - you may need more mass rather than less.
If you need less mass, the resonance would not be audible as runaway bass - you might see woofer pumping, but it would all be sub-sonic... it would affect high frequency tracking rather than bass.
But if the resonance is too high (need more mass) - then your can get a massive bass boost.
HTH
bye for now
David