I'm glad things are improving, slightly.
Just some food for thought...
If I were you, I'd really try to play those records which you feel have distortion on someone's table who knows they have a solid setup. Just to rule that out.
If you are hearing distortion on certain records, and now you are hearing it still, on technically a nicer more detailed setup, either in more or less amounts... it could be the records buddy. Could be, not necessarily.
I've had used records gunk up carts before. I've had a used record, I'm fairly certain, which actually bent a cantilever.
A few months ago I got a New record. Gave it a quick wipe and threw it on. Terrible sounding. I inspected the record closer, there was a thin, thin residue of something on it, barely noticeable. Glue or something. I was able to clean the stylus thankfully. And I trashed the record.
Are you using the same phono pre on both tables? If so, diagnose it.
Are you using the same amp? Same speakers? Make sure you rule those out as culprits. (Most likely they aren't. But check everything.)
Are you hearing distortion in just one channel on both tables?
There are many factors to diagnose. My main concern is that you are hearing the same issue, on the same records, on two different tables.
Again, I run a few Ortofons. No IGD issues. Specifically, I run a Silver, also bonded, almost identical to the Red. Its not my best cart, but it's not bad at all. And no distortion.
Good idea, I'll try to find someone with a great setup to test out these records on. There are definitely a couple of albums I own where there are known issues on the pressings, I've seen comments on their Discogs listings about IGD on certain songs. That said though, there are a couple of other albums where I notice more sibilance now than I did before on my LP60 (moreso sibilance than distortion).
And yes, I'm using all the same equipment on both. Again, there are some albums where I definitely notice a big improvement in sound, the treble boost really helped open them up!