customer moved office people which means i moved ext's.
I used the existing house wire. Tested with another ext phone.
All works except the LCD screen is blank. When i move the phone back to it orginal ext location
the LCD screen is ok. I did't think T&R matters. Any other thoughts.
Thanks Gary S.

It's been over 20 years but....I think, LCD contrast is stored on the system of the port and not the phone itself.

If that is the case, adjust the LCD settings at the "new" location and see if that works.