Pro-Ject Debut Carbon DC with Ortofon 2M Red Cartridge: BASS sounds 'muddy' The Reason?

Some tracks sound good and others not so much.

This makes me think that the issue is the source material itself unless as was stated the bad tracks are always at the beginning or the end or in the middle of the record which would then indicate a setup issue.

The Bass is prominent and not ’tight’

This could be your cartridge picking up secondary vibrations  from the bass being transmitted into your room from your speakers with those vibrations being picked up by your stand, turntable and tonearm and then being picked up by the cartridge and resent through your system.

This was an issue I had about a year ago. I was able to mitigate it quite a bit by purchasing some ant-vibration pads. The pads I bought were about a 1/2" thick piece of cork sandwiched between two pieces of rubber. They were somewhere between $10 to $20 for a package of four off of Amazon. Ultimately I ended up with a Townshend Audio Seismic platform. Substantially more than $20 off of eBay but it did eliminate any acoustical issue I was having with my turntable rig.

OP sent the table back from whence it came.

I’m thinking if it was a problem with the Project TT then the muddy bass would be prominent on ALL recordings which is not the case.

The other question I have is whether it’s better to buy a ProJect Debut Carbon DC and significantly upgrade the cartridge ($800 for example) and other tweeks or buy the Technics SL-1210GR (and buy a cheaper cartridge ($200)

Finally, will upgrading the pre amp/amp solve the muddy bass problem.

Again, thanks everyone for your help you’ve been very helpful!

Klimt

You are answering your own question. Get the better table.
BTW, bass varies by record. Just because some sound better than others doesn't mean the fault is not in the table/setup.

That table certainly does have a VTA adjustment. Also, I recently bought an Ortofon Quintet Red MC (cheapest of those 4) for my Linn Basik/Akito table and it sounds great. Highly recommended. I'd been using the excellent but underrated Sumiko Pearl MM for years and THAT sounded great also, but wanted to try a MC cart...after some break-in it just sounds fabulous.