I know, and I understand that it's pretty pointless to be asking questions about a problem that is fixed. I just enjoy bike mechanics and have a hard time letting go of this issue without understanding what went wrong. After all, it looks fine, seems straight, and operates well with the exception of the fact it slips. A few days ago, prior to me asking here, I put the Altus back on. Sure enough, problem came back. Put the LX back on, mashed the living crap out of that bike, not a single issue.

Like I said, just trying to learn as much as possible. I know it's hard to diagnose over the internet, but I figured I'd take my chances.