Having trouble reducing the vibrations on my turntable setup

Any shelf will vibrate at a certain frequency. Depending upon that frequency, there will be regularly spaced nodes that remain stationary even while the shelf is energized and vibrating. If you can locate those stationary nodes and place the points of your cones directly on those areas, then the cones can provide isolation. But it's very tricky to locate those nodes.  

Oh, it's not tricky at all- they are all over the place! Problem is, they move around depending on the frequency. That's not the worst of it. Look how many there are in the midrange frequencies where we are most sensitive! 
https://youtu.be/WmwnN_T_wW8?t=40

I have a friend with the clear audio table and he uses Pneupods by Pnueance Audio. They make special adapters that allow the pnuepods to screw right on the bottom of the table replacing the original feet. You can knock on the platform the table is sitting on and the feet prevent vibration. He hears no thud out of his speakers and has no feedback either.

Sorry Pneuance audio check music direct 

Have the stock tip toe feet (3) on my music hall mmf-7.3, resting on a butcher block acoustics (maple) 1 3/4 thick isolation platform which rests on 4 rubber bushings which are integral to an Apollo turntable wall shelf. My turntable is as quiet as can be. Black backgrounds and silence during quiet portions of tracks. Albeit, on older worn records, I of course can hear a pop here, a click there etc...thats vinyl for ya. One word of advice, stop tapping and knocking on the turntable or what it rests on! You are of course going to hear something if the volume is raised...you will Never eliminate it totally with whatever gadget they are pushing. Reduced, maybe. Eliminated? Never. Just play your records and stop obsessing. ALL JMO.

MC, Nodes for vibration should not move around.  However, the number of them might go up or down depending upon frequency.