PartnerPlus 206E R3.1 only 1 port for 4 wire phone? 1

Hi All.
This Partner Plus system was here way before our company and nobody knows more than 'It works! If not--> restart and re-seat!'
Last week one port on a 206E R3.1 died. I was able to call out, but nobody could hear me. Phones, plugs and cables triple checked. No dice. Boss said 'Grab one off the 206E modules from the shelf and add it. Gives us 8 more ports".
Well, he was right.We have 8 more ports, but only one works for system phones (MLS-12D) on all the other ports the phone is dead, only 2 wire phones have a dial tone and work.
He keeps telling me that this programmable what phones each port supports. I can't find anything in the manual or the internet about this setting and think this is just another very old,(partially) broken module.
I tried the copy settings function, but that did nothing.
Is there really a way to get system phones to work on all ports other than a board repair?
I'm obviously not a phone system technician and any help is highly appreciated.
Thanks.