Did you do the basic troubleshooting of swapping CO-7 through 10 with CO-1 through 3 to determine if the issue is with the Partner system or the telco?

Have you swapped the old and the new 206 modules to determine if it is associated with the modules?

Do you have a PC card in the ACS? If so, back up the current configuration to the PC card, and then do a factory default. Now with all lines assigned to all extensions, and no restrictions, what happens? You can always do a restore to get back the original settings.