What do I have ??? Help....

It sounds like your slide assembly is installed backwards. I recommend you write this in the "Ask Harmonica Expert Winslow Yerxa" part of the forum... Winslow is more familiar with chromatic harmonica construction and can give you step-by-step instructions.

Let me ask a primary diagnostic question.

With the slide out, what is the pattern of small, square, open holes inside the larger round holes of the mouthpiece?

If the open holes are in a straight line and not in a sigzag pattern, you have an instrument much older than 20 years; more like 50 years old. This arrangement is know as straight tuning.

If the open holes alternate between the top and bottom half of each successive round hole, then you have the more recent cross tuning.

If your instrument is straight tuned and the bottom halves of the holes are open when the slide is out, then the slide has been flipped. Some players prefer to have the note go down instead of up whe they press in the slide and will flip to the slide to effect this. It's known as flat-slide setup.

Straight tuned Hohner insturments can be converted to flat side by simply flipping the slide because the slidepring intersects with the slider at exactly half its height. On cross-tuned instruments the slide spring is higher up, so a new hole must be drilled in the slide with great accuracy of loation - it's not a casual change. That's why I suspect you have an old straight tuned harp. 

You can re-flip the slide if you're careful, reasonably handy with a screwdriver, and have the patience to align some fiddly bits.

First let's look at the layers that make up the slide and mouthpiece assembly.

Let's start with the body of the harp, consisting of the reedplates, comb, and covers.

The Backing plate. The front of the harp presents the fort edges of the comb and reedplates. These may not meet to form a erfectly flat surface, so a backing plate is laid on top of the fron of the harp. The backing plate has a grid of square holes to let air into all of the chambers in the harmonica. You may notice four notches in the backing plate. These receive the tabs that prorject from the U-channel.

The slide is laid on the backing plate. The slide has a different arragement of holes so that only half of the chambers are open in either the slide-in or the slide-out position.

The U-channel is laid over the slide. It has not only a long flat surface, but sides that bend at right angles, giving its profile a sorts of squared-of U-shape. The U=channel and the backing plate together form a cage that allows the slide to move freely.

NOTE: Straight-tuned and early cross-tuned instruments have a U-channel. Later cross-tuned instruments incorporate the U-channel into the back of the mouthpiece.

The mouthpiece is the top layer in the sandwich.

There are a few other important parts as well:

• The slide spring is what makes the slide spring back to the out-position when you release the button. This is a piece of very stiff wire with several turns that are wound around a post inside the comb of the harmonica and two arms that project out from the coil. One arm is long enough to stick out past the backing plate and through the slide. Slots are cut in the backing plate, U-channel, and even the back of the mouthpiece to allow for travel of the slide spring.
• The slide bumpers are small cylinders of soft rubber or plastic that encase the mputhpiece screws between the mputhpiee and the comb. Their function is to prevent the slide from hitting the screws, avoiding both noise and damage to the screw threads.

To un-flip the slide you need to disassemble the slide/mouthpiece package using these steps:

1. Unscrew the two screws that hold the mouthpiece in place.
2. Lift the screws and mouthpiece away from the harmonica, being careful to preserve the slide bumpers.
3. Carefully remove the screws and also the slide bumpers, or soft rubber bushings that encase the screws to prevent the slide from striking the screws.
4. Lift off the U-channel.
5. Lift of the slide, disengaging it from the slide spring.
6. Lift off the backing plate.

At this point, you may find that the parts are all rather dirty. Clean them with a toothbrush and some non-abrasive and nontoxic soap or cleaner, by laying each on a flat surface (the slide button should overhang the edge of the cleaning surface so as not to bend the slide when pressing down while cleaning). Use a toothbrush. DO NOT GET THE COMB WET if it is made of wood.

Once you've cleaned the parts, reassemble the package in this order:

1. Thread the mputhpiece screws into the mouthpiece and install the slide bumpers.
2. Lay the backing plate on the front of the comb.
3. Lay the slide on the backing plate. If it lies so that the top half of Hole 1 is exposed in the out position, you have it right-side up.
4. Engage the slide spring in its hole in the slide. 
5. Lay the U-Channel over the slide and engage the tabs in the U-channel into their notches on the backing plate.
6. Thread the mouthpiece screws through the holes in the U-channel, slide, and backing plate and into the comb.
7. Lay the mouthpiece on the U-channel and press in the middle area, halfway between the left and right side of the harp. With your free hand, gently tighten the mputhpiece screws. until they are almost snug.
8. While continuing to press on the mouthpiece, test the movement of the slide by wiggling it in and out. It should move freely and should spring back. If the slide spring has disengaged, you may need to dissassemble everything and re-engage the spring.

Final tightening of the mputhpiece screws is the last step. You want the screws to be tight enough so as not to leak air, but not so tight that the slide binds - refuses to move or moves sluggishly.

To do this, start with both screws a little loose. Tighten one until it binds, then back of a quarter turn. Then do the other one. You can go through several cycles of fine tuning the tightness of the mouthpiece screws.