The AE finder on my SQ-A has started to give inaccurate readings, leading to photos that are 1-2 stops underexposed. It was working fine as recently as this past summer. I have cleaned all the contact points on the finder and body and lenses, and confirmed that it does this with multiple lenses. Is there anything else I can do myself before giving up and shopping for a new finder or sending it in for repairs? What causes these meters to go bad?