@spatialking I haven't read through this entire thread. So, if this has been addressed by others, my apologies.
First things first. Are all the electrical connections in good order (cart leads; TT wires; etc.)?
Secondly, Have you got your records stored in good quality anti-static sleeves (e.g. MoFi inner & outer sleeves)?
Thirdly, what is your TT sitting on?
Fourthly, is your TT next to any piece of equipment that generates a high level of EMI (electromagnetic interference - e.g. satellite TV receiver(s)?
Fifthly, I know there are those who think playing records with a dust cover in place is the spawn of Satan. However, provided everything is set up properly and you have a good TT, properly fitting & substantial dust cover, etc., I haven't noticed any difference in sound quality with the dust cover closed. As such, I would never play records without the dust cover down. Dust is the enemy!
Lastly, do you have an use a record washing system?

