Yeh, clean up that corrosion on the board mounting brackets. What I do is use a good wire brush to get most of the corrosion off, then soak in C-L-R (50% water and 50% C-L-R) solution and scrub again with the wire brush. Rinse the part with warm water. Now spray with Mean Green (or other household cleaner like 409 or Fantastik) and rinse again. That final spray of the household cleaner halts all of the C-L-R action. You can now either tumble the bracket or polish it with Brasso or Simichrome. A nice clean, shiny bracket will now have a good ground connection to the board.