"REGISTERING"

I appears these phones did not get the new firmware. I have some 7975s that are fine, but some that are on the old version. I've tried setting the "Create CNF" files in system parameters, and have reset the TFTP servers, though this hasn't resolved the problem.

do you have all your 7975' on the same device pool?

yes. Same subnet too ... phones are adjacent to each other and the network config looks good.

check the device defaults configuration and make sure that the default device pool matches the device pools that are assigned to your 75s

Checked that already. The working 7975s have the load indicated on the Device Defaults, the non-working 7975s have an older version ... they just aren't upgrading their firmware.

why don't you hardcode the firmware under the phone settings .. phone load and shut down the switch port and bring the port back up

let me know if that helps