Is my Cisco switch port bad?

Solution 1:

While banks of ports often share an ASIC, each has to have its own separate PHY. If the PHY has been damaged it could very have a problem while its neighbors don't.

That said, output drops are an odd symptom for a physical problem - not impossible, but not typical. Notwithstanding half duplex links, output drops usually have more to do with buffer exhaustion than physical problems.

You may get more information by setting up a packet capture on the other side of the wire. A bad PHY would be expected to manifest with some number of physical layer errors (bad CRC, runt/giant, etc) on one or both sides of the link.

All in all it sounds like you've eliminated enough that it may be past the point of diminishing returns. I'd recommend an RMA if you have a contract.

Solution 2:

Yes, a single port can be bad, but as I recall, you have to replace the entire module. (Caveat: it's been a long time since I've done significant Cisco work...)

I'm not sure if it can help, but check out FITB, by Laurie Denness, one of the Ops engineers at Etsy.