I think this is covered in the "Tweeks" section plus many many threads. However, I would start with a simple but good vacuming.
Unplug the speaker for a day or two ahead of time and do both sides (the front more than the back if you have the time). Don't forget to plug them back in, they don't play very loudly if not plugged in.
I think some of this information is in your owners manual.