I don't know much about damping 301/401 chassis but just in case, I built a plinth once which isolates the deck totally from its plinth and the plinth from wherever I set it up. The isolation is by means of butyl pads and tubes and works for me.
According to some internet legend, the platters allegedly ring like bells. Whether this is so or not, has never bothered me.
I once read somewhere, a 401 owner poured melted rosin in his platter which apparently had a beneficial effect.
Wiser VE members will no doubt dispense better advice.
"If you don't like my principles, I have others" - Groucho Marx