Sub Sonics and woofer pumping

Last_lemming, are you saying this occurs with more than one record??
the lead in grooves seem to be the noisiest park of the record. If this is just one record you have either a warp or a low frequency pulse at one point on the record. No big deal. If it is happening with every record you have a much more serious problem with the bearing or platter. The Cartridge is doing what it is supposed to do. If you are worried about the tonearms resonance frequency get a test record and check where it is. Very easy to do. 

Woops Wrong test LP. This one  https://www.amazon.com/HIFI-NEWS-Test-Producers-Cut/dp/B00KMCL1PE

Last_lemming are the woofers pumping at normal listening levels or just when you turn it up?
The Nagaoka is very stiff and we really do not know where you are.
It would help if you could get the Hi Fi News Test LP. Then we can know for sure. It also is a lot of fun to test other parameters. Very Useful.
Here,  https://www.amazon.com/Tonearm-Headshell-Cartridge-Weights-turntables/dp/B01B8ONJVI and  https://www.amazon.com/Ultimate-Analogue-Test-Lp/dp/B001GBA71Y/ref=asc_df_B001GBA71Y/?tag=hyprod-20&linkCode=df0&hvadid=312149562874&hvpos=&hvnetw=g&hvrand=501746434509243117&h

Last lemming, you have several problems culminating in amplification of rumble. The most significant one is that you are using a very stiff cartridge in a uni pivot arm. Your resonance frequency is too high and you are amplifying rumble inherent in records. You will need to add mass to the head shell. In order to determine how much you will need a test record with resonance tracks like the Hi Fi News Analog Test LP. You want to get that resonance frequency down below 10 Hz. Uni pivot arms are a problem because they have a third degree of freedom and a third resonance point, the rotary one. The best way to avoid issues with rotary resonance is to use a compliant cartridge like an Ortofon 2M series cartridge. They run around 20 X 10-6 cm/dyne. The Nagaoka is 8.5 X 10-6 cm/dyne. It is a great cartridge but it was designed for a heavy gimbal arm. I think you can get the rumble down to acceptable levels by tuning the system. If you can't then there are only three solutions, change the cartridge, change the tonearm, get a rumble filter. My preference would be a new arm. The Nagaoka will work perfectly in an Ortofon arm and they are relatively inexpensive. Soundsmith sells a dandy set of graduated head shell screws. Put the heaviest (Stainless) screws on and tell us what happens!