This Woofer pumping can be a real problem, first I would check cartridge compliance with tonearm just to be sure...MORE than likely it is the room your system is in! move it to another room or get some major sound absorbing (pillows are easy for testing ) materials and try them out in a few key locations, Get a heavy slab of granite under your turntable, move the sub around or angle the mains a little differently, you need to change the frequency in the room! 

P.S. Don’t bother with a KAB filter, unless you like the sound of a blanket being thrown over your system.

Matt M

I’ll also add that your turntable behind the speaker is probably collecting bass standing waves and passes it through the record into the cartridge then into phono stage. Try moving the stand with the table more into the room. 
You need a component rack man. Badly. This is good stuff https://upscaleaudio.com/products/solidsteel-s3-series-audio-stands
 

I use Solid Steel stands. Table is right next to the speaker - zero issues. 

This took care of the problem for me.

https://townshendaudio.com/product/seismic-platform/

One more thing!!

Can a Turntable Dust Cover Cause Acoustic Feedback?

On a well‑isolated turntable, the dust cover generally does not cause acoustic feedback. Its main purpose is protection, and in a stable setup, removing it usually makes no noticeable difference in sound quality  .

However, on a less stable setup, the dust cover can act as a resonator or vibration path. If the lid is thin, hinged, or placed on a lightweight or resonant surface, it can pick up vibrations from the table, speakers, or nearby objects. In such cases, the cover can amplify or transmit vibrations that might be perceived as feedback or unwanted noise