Vinyl Newbie - So Many Questions!

doodledan, if your motor is sliding around, try sitting it on some dampening material. That is, if it doesn’t cause a height issue with your belt. Herbies Audio makes some thin but affective dampening sheets which may help.

Additionally, I agree with the previous comment regarding the level of your tonearm. Just for grins, can you raise and lower your tonearm by around 1/16th and play it in those varied positions? With the head shell slightly raised, you ought to get a fuller richer sound. With the counter weight slightly raised, you should get more detail.

The difficulty with this problem is why your noise problems are inconsistent.

I have a Linn with a heavyish platter. I always hand start it by spinning it first. Otherwise you will soon stretch the belt.  With this assist, belt lasts almost forever. 

I've had a look at your TT Model and it is a model that has quite a few good appraisals, it looks more than adequate to support your needs at present.

I've had quite bad experiences with Modern Pressed Vinyl sourced through the larger supply chains.

Fortunately these purchases are supplied with good returns policies, so it is prudent to choose to make use of this side of the service.

Also a MFSL LP might be a bit more pricey, but can prove to be a good benchmark to compare other vinyl purchases against, when another LP is noticeably inferior in the comparison, returning it and receiving another copy will in most cases prove to be a corrective measure, where a noticeably improved LP is received.

Avoid buying discounted copies of a New Release LP from larger supply chains, as these are possibly items that are already returned by customers.

The TT Belt on your TT, is claimed to be a Silicone Material, is there any sign of a wetness on the belt, as a Silicone Oil residual can easily create a slippage.

The TT's motor is a design that is very accurate for speed stability and I doubt if it has a fault, but maybe should not be ruled out.

The Stylus being quite dirty can cause a replay to sound quite distorted and unenjoyable, or worse a damaged cantilever can produce a replay that sounds very incorrect and concerning. 

It looks like there is a bit of hill to climb, to get you to the place where the Vinyl side of the system, is proving to be quite satisfying.            

Goofy, I don’t get the impression that some LPs play fine, just that some are less objectionable than others.

I reviewed the Marantz TT user manual. Since Marantz sells the TT, the phono cables, and the Virtuoso cartridge as a package deal, it seems unlikely that cable capacitance would be an issue, although the Zen has a highish input capacitance, and I can still easily imagine the cables add 100pF. However, the OP needs to check out setup first, VTA, VTF, grossly accurate alignment. As I inferred above, one possible way to ameliorate the effect of the high capacitance load on the cartridge is to reduce the input resistor load, which is to say reduce its value which paradoxically increases the load on the cartridge by a tiny amount. I still think it would be worthwhile to try 33K ohms. The only way to do that with this rig is to insert a resistor in parallel with the fixed47K load. This can be done with the inexpensive kit sold by DB systems.

i just looked up the loading kits made by DB and sold by Acoustic Sounds. It’s mainly for MC cartridges, but they do include a pair of blank adapters that could be used for any value needed.

You have a decent turntable.  I owned a Clearaudio Emotion for quite a while and it is very similar to your table.  You have a really cheap phono stage.  

Here are a few suggestions.

Try getting a really thin sheet of sorbothane and setting the motor on that.  Thin being the key, if it's too thick the belt may ride too high and come off the platter.  The sorbothane can leave stains on things, so take that into consideration.  Blue tack might work.  The thing I least liked about my Emotion was that the motor could move around.  The sorbothane really helped.

Don't be afraid to give the platter a little spin and give the motor a little help to avoid the belt slipping.

The ticks and pops become less noticeable as you get better gear.  People are often surprised when they hear a really good analog setup and it's dead quiet.

Many new pressings have a lot of ticks and pops.  Static electricity can also be an issue.  Cleaning records can help with this, and there are devices that are purported to reduce static (I haven't tried any, so won't comment on their efficacy).

There are places you can get information on the quality of different pressings.  The Steve Hoffman forums are one and you can also look up the release on Discogs and see ratings and often there will be comments about the pressing quality.  Unfortunately, it's often a crap shoot - one person will get a great copy and the next person will get a poor copy.

If you are open to an upgrade, check out the Parks Puffin.  I think they are under $500 new.  It's a great phono stage at its price level and has a "Magic" setting that will reduce clicks and pops.

If you have a hi-fi shop nearby, take the table in and have them check your setup and the cartridge.  That shouldn't cost much.