You used to get special stylus cleaning ‘brushes’ which have a circle of very close packed short bristles which you put a few drops of a solvent to remove detritus that builds up on the stylus over time, mostly dust that sits in the grooves and isn’t removed by using a carbon fibre brush. I can confirm that it can really build up into a lump that’s actually difficult to remove with a regular brush, especially with older vinyl, and can really cause distortion.
There used to be a system that involved a tube full of liquid with a brush on the end that sat on the record on the opposite side to the tone-arm, so the stylus would actually track in liquid. Problem is, all the dust that settles on the record just sits in the liquid until it dries, then it sinks into the grooves and becomes like mud; a friend used it, and albums I played on his deck really suffered because this crap would stick to the stylus a hard lump, and was really difficult to remove.
There was another way of cleaning the stylus using small strips of plastic with a rough surface, a sort of benign abrasive, which worked very well, but you need to turn the volume right down!
This was used on Japanese cartridges costing thousands, so perfectly fine for cheaper AudioTechnica cartridges, you just need to be careful, and maybe use a magnifying glass to see what you’re doing.
Double checking tracking and bias won’t hurt, either.
I’ll have a look and see if I can find sources, I’ve still got my turntable and all the odds’n’sods I accumulated for cleaning, so I know what to look for.
Right, the nearest to what I have, which is D3 cleaner, is this:
https://www.directaudio.net/products/mobile-fidelity-stylus-cleaning-fluid-cleaner-lp-9
Not cheap, by any means, but it really does work, if my similar system is anything to go by, this is what mine looks like: