I would not worry to much about pests since the port has a screen.
On regards to the vibration, it could be three things that happen to my Algonquins. First, remove the woofer and find the loose washer that would of held the bolt from the inside. This will cause some vibration noise inside.
Second, check the port screen. I found that in one of my speakers the port screen was loose and created a ratteling noise. Tried to glue gun it, but did not work.
Finally, also check the wires inside to make sure they are not vibrating and causing some noise. I used the cotton mesh inside as a buffer for the wires. Hope this helps.
j
