The original specifications for this turntable were that rumble was -57 dB below "average" recording level, whatever that was. This turntable was cleaned up, adjusted and its steel spindle ball bearing was replaced with a ceramic ball bearing.  Here is the signal to noise ratio noise spectrum relative to a 5 cm/sec recording level:

Note that the noise dramatically increases at all frequencies below 500 Hz.  Although it met the 57 dB spec, it was not pleasant to which to listen.  When playing records, one could plainly hear the whirring sound of the motor coming thru the loudspeakers along with a low frequency purring.  If one did not want to hear unpleasant noises, one had to play the music at low to moderate levels.  Quiet classical music was greatly degraded.  Like listening to Mozart in a bowling alley!

The original rubberized belt and original, yet still-pliant, motor grommets were replaced with our rubber belt and Rumble Reducers.  This was the result:

Mid frequency noise is 7 dB down and low frequency noise is 15 dB down.  Motor noise is not audible, even at high levels.  The resultant turntable noise levels are equivalent to modern audiophile turntables.