In order to raise the metering needle a half step or so, a small diameter (less than 7mm O.D.) washer is placed on the needle just under the e-clip. This raises the needle by about .5 to .8 mm depending on how thick the washer is. However, there is a problem with simply putting the washer under the clip. The slide has a relief cut into it to hold the e-clip loosely. The increase in thickness from adding the washer causes the needle retainer to bind the e-clip in position. This prevents the needle from self centering in the needle-jet and may even cause the needle to be fixed at an angle. This leads to a lot of wear in the needle-jet and the actual clip groove in the needle. To prevent this, a spacer is necessary to raise the needle retainer slightly at its perimeter. The spacer needs to be at the perimeter so the needle retainer won't sit at an angle, as might happen if a central washer was used as a spacer. An easy way to achieve this is to use a shim wire of appropriate thickness, formed into a ring, inside the slide, under the needle retainer.

One good source of shim wire is guitar strings. Stainless steel or phosphor bronze, acoustic guitar strings should be good for preventing reaction between the brass slide and the string. (That area stays dry and clean, normally.) Most guitar shops will sell you single guitar strings relatively cheaply.

The size of the string will take a little trial and error to get right. Guitar strings are measured in thousandths of an inch. The actual thickness to get depends on several factors. First, obviously, the thickness of the shim washer will affect the final size shim wire to be used. But in addition to that, e-clips vary in thickness depending on whether you are using factory e-clips, e-clips from a rebuild kit, or e-clips from a Dynojet kit. Another factor is the amount of chamfer on the perimeter of the needle retainer. The chamfer creates a groove between the retainer and the slide wall for the shim wire to sit in. This groove may be different from carb to carb (usually not, though) and since different thicknesses of wire will sit differently in the groove, it is difficult to predict what size to use. It is best to get a few sizes of shim wire.

Most shims will be around .5mm to .8mm thick, so from trial and error, shim wires (guitar strings) in the range of .024" to .034" will work.
For a .56mm shim on a factory needle, use .026" bronze wound guitar string.
For a .57mm shim on a factory needle, use .026" bronze wound guitar string.
For a .63mm shim on a factory needle, use .028" bronze wound guitar string.
For a .78mm shim on a factory needle, use .034" bronze wound guitar string.

For a .57mm shim on a Dynojet needle, use .026" bronze wound guitar string.
For a .61mm shim on a Dynojet needle, use .026" bronze wound guitar string.
For a .78mm shim on a Dynojet needle, use .034" bronze wound guitar string.

To form the string into the correct size ring, an 8 mm bolt seems to work just about right. Simply coil the wire tightly around the bolt a few times, then let it loose and cut it to length. Cut it so there will be a small gap in the ring when it is installed. The ring should open up slightly larger than the inside of the slide so it will act a little like a spring, and hug the walls of the slide. Too much spring and it will want to pop out. Not enough spring, and it will not hug the wall.

Here's the inside of the slide before the shim wire is in place.

Here it is with the shim wire in place.

Now, when the needle, shimwasher, and retainer is installed, there should be little to no axial play in the needle, but it should wiggle slightly and rotate easily. If there is no axial play at all, or the needle is still bound, then the next size larger shim wire should be tried.

Note: shimming the slide with a wire will cause the slide position to be lower at wide-open-throttle. This can be corrected by adjusting the throttle stop as described on the maintenance page: TK-22 adjustments and maintenance. This limit should be checked anyway since they often come from the factory with the stop set so the slide can open beyond fully open. This leads to a rich condition when the throttle is turned to the limit.