Tracking down cause of distortion on vinyl

Hi all -

Recently LPs on my modest system (Technics SL-1200 w/ KAB Groovemaster) have been sounding off - kind of thin and distorted, especially on loud tracks or passages. The stylus on my cart was destroyed by someone in the house, and I had to replace it with a JICO back in February. The JICO was fine at first (although the suspension was not as good as the original - did not track as well and needed higher force), but I have heard they have quality control issues and suspect that is the cause. But how can I actually verify this?

Is it worth getting a test LP (I hear mixed opinions on the worth of these) - is there anything typically there that would isolate mistracking, say, as the cause?

I love the cartridge, but don't love the idea of ponying up for another questionable stylus (assuming I'm unlikely to get any credit on it now), if that is indeed the problem.

Also, is it true that if it is mistracking badly it is damaging any vinyl I put on?