Thought I’d resurrect this worthwhile old thread. I have found this to be true on virtually every speaker I have owned. I disagree about doing it every two weeks as someone mentioned above, but once every 2 years is about right. I also don’t agree that it is strictly or even primarily about the expansion/contraction of mdf - over 40 years in the hobby and I have found that tweeters rarely get loose, and I have found that woofers get loose even on Wilson speakers which are made from materials designed not to expand or contract. It’s about the movement of the woofers, and it cannot be avoided. Be gentle and be VERY careful of the powerful magnets which can rip the tool from your hands. I would NOT recommend Loktite or any other foreign substance or modification (such as bolts instead of screws) unless you are confident that you can reverse it without consequence. Such modifications WILL alter the sound of your speakers in unpredictable ways, while merely snugging up the drivers every couple of years should be considered ordinary maintenance that will keep your speakers sounding like new.
Enjoy!!
Enjoy!!