Why are my woofers pumping?

Just as a FWIW- the digital recordings you made may not have the subsonic information that is pumping your woofers, so I would not use such recordings as the results might be inconclusive.
Have you tried greasing the platter bearing yet?

Atmasphere - thanks for hanging on, what would A-gon do without such good advisors.

Today I received the millimeter version tool that should help tighten the housing of the Hanss bearing. When I get my friend over we will turn the whole heavy player on its side and then try to tighten it. We will also give the bearing a bit more oil - this should be just thin "sewing machine oil", says some audo importers over here - Hanss does not specify.

My suspicion is: it won't make much of a difference. But we'll see.

My short summary, so far.
Vinyl rips from my main rig, made on my DSD recorders, played back at my modest cottage system, are able to reproduce subsonic pumping. When I play digital including advanced digital at the cottage system - SACD - there is no such pumping. With vinyl yes, some pumping, varying with the record.
This seems very similar to my findings, regarding my main system at home.
The pumping seems to happen with the cart-arm combo regardless of the player (VPI vs Hanss) - although I have not checked this much.

My audio friend Eirik came around today and helped me tighten the housing of the spindle on the Hanss player. Luckily the needed 2.5 mm Umbraco driver was included in the set I had bought. So - what was the result? Pumping: no difference. It did not go away. Sound: maybe a tiny bit more relaxed, less tense, but this may be my imagination. Eirik brought along some fine-sounding records and we played tracks from the Mofi edition of Dylan's Another side, and from the reissued Grateful Dead Cornell 1977 box. They sounded very good, and neither he nor I could find any clear indication of too much rumble. But he did remark on the LOOKS - the visual (subsonic) pumping of the woofers especially between tracks. It does not look like that in my system, he said.

Dear @o_holter : Two question, how is conformed your system speakers and its frequency response? is a passive design or active? two subwoofers or none? well more than 2 questions and other one.

I posted before that could be a good test to try to borrows a full SS phonolinepreamp instead buklbs you are using. I think you have to have that test, is a must.

R.