I have a 550d and the display in the viewfinder seems to be failing. The display for the aperture, shutter speed, iso etc. Seems to have randomly failed parts and some parts fully lit. The camera is about 4 years old. Anyone know if this is a common fault or just needs a new internal battery (seen an odd post elsewhere which seems to suggest this may be the issue). Any info gratefully recieved before I decide whether to send it off or live with the bust display.