empire 980 arm mistracks with various cartridges

Hi I have Empire 598 with 980 arm that mistracks with all cartridges used. All carts function fine in other turntables.
No matter how heavy I set up the VTF going way over limit of the cartridge specified it will still mistrack and would not output anything bellow 160Hz. So all bottom end is completely sliced away. When I tap on the plinth, bass comes back for the flash moment.
So far connected ADC Series II, Pickering XV15, Shelter 501 with no success. What may cause such brutal mistracking and lack of resolution?
Have you adjusted the arm height? That can play a significant role in the bass playback.

Also, the plinths on the original Empires are pretty well a joke. They resonate quite a lot. Also, the bearings in the 980 are quite fragile and they may not be functioning as designed.
Hi Ralph, I've tried ALL heights possible and they all sound same. My empire has suspension plinth and is one of the decent ones. I'm thinking about fitting different arm do you have anything in mind for the tight budget?
It's probably your bearings. Carefully place a 1/2 inch square of plain paper on the tonearm gently while it's floating at zero grams - if it does not move, you have too much friction.
I think that arm-tube bearings at least one is loose -- the one opposite to VTF dial adjust. Any options to pack it with some light grease?
I'll appreciate responses!
If adjusting arm height has no effect on the bass the arm is having a severe problem!

The bearings don't go out of adjustment, unless someone messes with them. They fail. Over-tightening the bearings is a simple way to damage them. They are supposed to be ever so slightly loose. They are not packed with grease- they don't need it.

The bearing is extremely loose, but not slightly. Main bearing too. There's not much of a friction issue, but lots of tracking errors.
I'll be replacing this tonearm with rec-o-cut s990 that will fit with no modification or suspension elimination.
THANKS for everyone's input.
I finally came up with great arm AudioTechnica 1005 that landed onto the suspension spider just like the original one.
The smallish disadvantage that there's no arm lift(may acquire and mount externally and absence of magnet to pull up at the end of the dead wax.
Cartridge being used is Pickering XV15 with D750 styli. I think this table may deserve better cartridge, but so far sounds fantastic. Can any recommend MM cartridge $150ish ballpark?
THANKS for input!
A Grado might suit nicely. I can't imagine the suspension of the cantilever is any good after so many decades.
Thanks Ralph,
I may try to look at Grado models at needledoctor, but probably will also try to slide a new needle onto XV15 cartridge that may be worth trying. Suspension of the cantilever truly not in the best shape, but visually unmounted looks perfect.
Suspensions tend to perish over time so they can look fine but not sound right.
Unless you have scanning electron microscopes for eyes, you can't see the deterioration of the elastomers used in cartridge suspensions.

You may see the result if the cartridge bottoms out. Long before that, however, you'll hear the loss of elasticity in blah dynamics and boring sound.
I however see that clearance between replacable needle chassis and playable surface is too low when landed with no scanning electron microscope or any optical devices in my eyes. It's not I believe because of 1g of currently applied VTF is too heavy...
The cartridge itself however sounds very clean, but will definitely hick-up or touch vinyl surface with replacable needle chassis if vinyl has humps or warps
Replace the stylus assembly. From your description it's worn out.

Even if you're okay with the sound, the risk of damage to your records from a cartridge that bottoms out and bounces the stylus around in the groove is not worth taking... IMO of course.
I totally agree and mentioned that I'm shopping for new needle(will still use that cartridge as a backup. super great for money indeed) and better MM cartridge. Budget Ortofon 2m series attract me the most for now.