not sure if this would fit into the category of software or hardware... but.. i have an old redhat 7.2 machine setup as a server with 2 wyse terminals attached to the serial ports. UP until recently they funcitoned perfectly and they still work almost perfectly.
the entryies in the inittab file seem correct
however when i log in... the TERM environmet variable is set at dumb and i have to set it manually, that and columns are set at 80 and i have to set that manually.. the configuration of the terminal itself hasnt changed that im aware of that could cause this.. any ideas?

Usually environment variables are set at login via a combination of /etc/profile, ~/.profile, ~/.bash_profile, ~/.bashrc, and so on... Perhaps one of those files has been modified, or you have started using a different shell by default (different shells use different profiles)?