[TVI-RFI-EMI] Green band on TV screen

[Clay T. Whitehead]

My son has moved to a new apartment and finds a green band at the bottom of
his TV screen when the TV is in the living room (most of the apartment).
Two TVs have the identical problem.  

Can anyone suggest a fix or a diagnostic to isolate the problem.  Sounds to
me like a magnetic field of some sort impacting the CRT, but I don't know
how to proceed.  Would a piece of screen wire shield whatever is the
culprit?

Thanks.
W6WW