handset lcd display breaking up/disappearing?

the lcd (?)display on the handset(s) of my AT&T 2325/2365 cordless phone 2.4ghz, is breaking up/lines across...on one, the display is so bad its unreadable...is there anything i can do to repair this ??? if not could a repair shop ? or would it not be worth it?? it seems like it shouldn't be difficult to fix as the phone was never damaged...what causes this??

judi
February 2009