Hello and Happy Friday everyone,

I've been working on-and-off to get this printer back up and running for about a month now, and have had mixed results.
It is an HP LaserJet 5000 with the additional 500 sheet Tray 3.

Trays 1 and 3 are working fine, no jamming, no pickup issues, no misfeeds, etc.
Tray 2, however, refuses to behave. If there's only a single sheet of paper in it, it will print properly. If I put more than that in, it will end up feeding a second sheet in right behind the first (not overlapping, I replaced the separation pad and fixed that issue). Most of the time this will result in a "Paper Jam" error.
I have replaced both the separation pad and feed roller for Tray 2; I have also tried an entirely different Tray 2 from another machine, with the same results.

The Configuration page reports 331995 pages total, and 8815 since last official Maintenance.

Any ideas on where I should look next? Or any more information required to point me in the right direction?
Thank you!