Steve, mics can essentially wear out, mostly from vibration due to transportation and changes in humidity, both of which effect the diaphragm.

I too had some Samson Q7 mics, mostly for use by others during a performance. Great mic, built like a tank, and outstanding frequency response.

Most of the time I used my Crown CM-311A headset mic, and though the fit was not as comfortable as I would like, it provided incredible vocal quality throughout it's range.

Now, I use a mic that DNJ recommended years ago, a Sennheiser E855, which provides outstanding results, has a wide frequency response range, excellent feedback rejection and no handling noise that I can detect.

Good luck on whatever you decide upon,

Gary