Resonance Problem

I use an Audiomeca Romance Table and an Audiomeca Romeo Arm with a used Grado The Reference MM low output (1.5mv) cartridge. I put them on the upper shelf of a Lovan Classic II Rack. When I play the records, I can see the vibration of the cartridge, and which produces a 10-20 Hz Severe Vibration on the woofers (B&W Nautilas 803).
My dealer told me that was caused by worned suspension of the cartridge. The Grado Lab told me the reason is the low effective mass (12G) of the arm, as Grado cartridge requires an effective mass of 12-17 grams with
optimum performance at 14 grams, and they suspect the tonearm is the problem.
Anybody has any suggestions to correct this severe problem.