Need help with HP-71 HP-IL Interface Module

[wallyhp71b]

I tried cleaning the contacts and no luck. I cleaned the contacts on the inside of the HP-71 & the contacts of the module and re-seated the module several times but the VER$ command still returns only "HP71:1BBBB" and doesn't recognize the module.

The odd thing is that I have a second "new old stock" boxed HP-71 HP-IL Interface Module 82401A that I have also just tried and it also is not recognized by the HP-71b when it is plugged in.

Maybe the problem is on the HP-71 side with its internal port, rather than either HP-IL Module?

I have other Application & Ram Modules that are recognized when installed and pass the ROM TEST 1G 2G 3G 4G.

Any more troubleshooting ideas that I could try?