B+O turntable problem

I have a B+O TX2 turntable with an MMC5 cartridge, which sounds horrible. The sound is rumbly and distorted in both the right and left channels. I am assuming I need a new cartridge, but I am not sure if that is actually the problem. I can get an MMC4 cartridge from Soundsmith, but wonder if I should or can do anything to make sure the cartidge is bad before I replace it.
just tell us where you have the turntable setup,on a seperate table,rack,wall mount or?
It is on a shelf of a buit-in cabinet. It is a pretty solid cabinet, built of 3/4 cherry plywood,the shelves have a solid cherry front edge, and they are dadoed,screwed and glued into the sides, which are screwed to the walls that surround the cabinet on 3 sides. The turntable used to sound fine, but the sound deteriorated to the point where it is awful. The Amp is on a shelf under the turntable, and one of the speakers is on the shelf above. The other speaker is on the top shelf of an identical cabinet in the other corner of the room.
Your speakers should definately NOT be in the same cabinet as your turntable. Also check your stylus pressure with a suitable gauge, and make sure that the cantilever/stylus assembly is not visually damaged using a magnifying glass.
sounds like your cartridge check that out first. And yes please take your speakers off the cabinet and place them on seperate stands or spike them to the floor.I would also place the turntable seperate from the cabinet, on its on.
I used hedphones to eliminate speaker contribution to the problem- and the same rumbly distortion was present. I pulled the cartridge and examined it and visually it was OK- no obvious signs of damage and the cantilever was straight and seemed to be in the right position and moved normally. It did not skate on records and tracked normally. I get sound from both right and left channels, but it is distorted, like being played through blown out speakers. I have read the "suspension" in the cartridges may "dry out"-could that be the problem here? Is there any way to check or repair this? I don't have a microscope to look at the tip, and wouldn't know what to look for anyway. I have seen a site (aminaaudio.com, aka Modular electronics, Inc. ) that says they rebuild these to be the functional equivalent of an MMC4 cartridge. I am aware that Soundsmith sells a new replacement for the MMC4 for $149. Any thoughts on either alternative? Anything else I should check before assuming my cartridge is a goner?
I am not familiar with that table but it would seem that checking the typcial set-up (VTA, VTF, alignment) would be something to check.

Benny at Amina/modular is top rate, really knows his stuff.