Sticky slide

You might check both the back of the mouthpiece and the surface of the slide for any bumps or other irregularites sticking up that might be contributing to wear. It's possible that the slide is slightly bent as well. One way to check is to find a known flat surface and lay the slide on it with the button ahnging of the end. Does the slide lie perfectly flat? If not, that may be the source of the problem. HOWEVER, bending a slide is a tricky business and can easily make the problem worse. Gentle flexing away from any bowing along the length is about as much as I'd attempt.Two things you can do without altering any parts are:

• Lubricating the mouthpiece assembly with misted water before and during play. Go to the travel section of a store like Bed, Bath and Beyond, or Walmart or a large drugstore. That's the mostly likely place to find, among the travel sizes of personal hygiene products, small handheld spray bottles that will spray a fine mist of water. Spray the mouthpiece and into the holes (but not too close maybe a few inches away) to add moisture to the slide assembly. This is the safest lubricant as it won't creep into the harmonica and gum up the windsavers.

• Use a very fine coat of vaseline on the slide. Very, very light. Suzuki actually makes a slide lubricating oil that is very light in texture but AFAIK you can't get it in the US. Brendan Power made a video where he slathers vaseline on his slides with what he claims are no ill effects, but gummed valves are what I'd feat from that practice.

Hope this helps.