Check the alignment with one of these Cartridge Alignment Protractors | Free Turntable, Tonearm & Cartridge Tools | Vinyl Engine
I t also sounds like a stylus force gauge would be useful with this deck. Sometimes the calibrations arn't accurate (I am presuming you zero balanced the arm before setting the downforce yes?) The Shure SFG2 is a good one.
If you still hear distortion after carefully aligning this stylus then the chances are the records are damaged, most likely by a previous worn or misaligned stylus. You can often get around this by changing the alignment method used.
In fact the chances are the Microline tip on the AT440 is tracing below any damage on the older records which is why they sound better, as back then more people would have had a conical stylus.
So by applying the opposite logic the damage inflicted to the newer records was most likely by an eliptical stylus, therefore using an old fashioned conical tip you should be able to trace above it.
Alternate tips should be available cheaply enough to the fit the AT440 or else get a cheap Shure DJ cart like the M44 and another of those Philips mounting plates.