Mike,
Remove the reedplate from the comb, use something thin enough to lift the reed (feeler gauge). Lift the reed aprox. 1/8" and allow it to slip from the tip of gauge/feeler and "plink" the reed, if the reed is unobstructed or otherwise good it will make a plinking sound. No sound, or a dull sound indicates that the reed is obstructed due to foriegn matter, like dried spittle, pocket lint, etc. If the reed breaks instead of plinking you indeed did have a crack in the reed and it needs to be replaced. While you have the reedplate out hold it up to a light source and look to see if the reed is centered in the reedslot. Hard blowing can cause the reed to cavitate and twist sideways causing the reed to jam against the slot at some point along its length. If the reed plinks, is not obstructed, or jammed in the reedslot, but is still flat you can bring it back into tune by filing material from the tip, last 1/4 inch. Filing form the tip raises the pitch, filing the first third of the length closest to the reedheel (rivet end) will lower the pitch. You can download a free chromatic tuner here
www.seventhstring.com. Look under utilities on the left of the page. Remember to calibrate the tuner to 442Hrz. Most harmonicas are tuned a bit sharp as the act of activating the reed causes it to flatten a bit. I hope this helps you out some, don't be afraid to lift the reed as I indicated, being a spring the reed can take quite a bit of lift before it bends. Good Luck! Super President
