I'm getting a buzz in the top left speaker of my 410 cabinet when playing at gig-level volume. It's not projected through the speaker, just the speaker itself buzzing. I took off the grill and tried to make sure the speaker was securely mounted to the cabinet. I noticed that when I push on the outer mounting ring/plate/whatever the buzz stops, so I figured that's what needed to be done. However, when trying to tighten down the mounting screws, one of them just spins in place. What can I do to fix this? Can I simply fill the hole with wood-glue, let it dry, and re-drill/screw?