Too Noisy / Not Tight Fit

We've been using this Philips Sonicate for years, and started buying the replacements from Amazon. They still work, but they do not screw on tightly, and thus make a loud noise while you are brushing. My husband gets very annoyed by this, but the knock-offs (sold from other companies) are even worse. I wish they were a little less expensive, but we will keep buying them...

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