I've had the same problem on my self-made cabs. The best solution I've found is a product called "E600" made by Eclectic Products, Inc. of Pineville, La. It comes in a 3.7 oz. tube, in black, (medium viscosity), and sticks to most anything; looks like silicone caulk - available at Amazon.
Last edited by eddiemac : 11-25-2012 at 05:07 PM.