I am using AIX 5.
Just swapped over an HP printer.
The old printer was on a JetDirect box. The new printer connects directly to the network. Using the same IP address to print to, so the only alteration I made was to edit the etc/qconfig file to alter the port setting from 9103 to 9100. I can print to the new printer. I can see the pages coming out. However, the jobs don't clear from the print queue. They are either showing as running or queued.
Did you try to remove the existing print queue and and re-add it after the new printer was in place? I think you use the fastpath "smitty mkpq" to get to the printer section of smitty.
Is the print queue currently using pcl or ps ? Perhaps the print driver needs to be updated / changed, depending on the emulation.