Adjusting a straight key 
Nancy Kott
WORLDRADIO FEB 2003

It is very important that these contact points are aligned concentrically.
If they are not, loosen the adjustment screws on the sides at the pivot
point and move the arm so the contact on the underside of t he arm is
directly over the contact point on the base. This can be a touchy operation,
so take your time. Be sure to adjust the screws on both sides as you are
tightening them up and that the contacts remain aligned. Tighten these
screws until there is no side-to-side m otion, but the arm still moves
up-and-down freely. It should feel secure, but not binding.
The gap between the contacts should be small. The thickness as a sheet of
paper, or a dollar bill, is about right size for the gap. Place a strip of
paper between the contacts and tighten the vertical adjusment screw until
the paper cannot be pulled through the contacts, then gradually turn the
adjustment screw until the paper can be barely pulled through without
tearing the paper. Then lock the adjustment screw in place.
Next, tweak the screw controlling the spring tension. Turning it to the
right will create more tension by compressing the spring, and turning it to
the left will loosen the tension. I recommend using a light spring tension.
As I have said earlier, using a key should be light and effortless, not
pounding and tiring. Having a lighter tension setting will also allow you to
send faster with less effort. It should not be so light that the arm does
not bounce back up, but you should be able to move the key arm down with a
very light touch. After adjusting the tension, you may have to go back and re-adjust the gap
space. Once you have it set the way you want it, tighten the lock nuts
securely. If you have been using a different gap size or tension, these new
settings may feel strange. But I promise it will improve your sending
speed and accuracy when you get used to them.
...Mount your key on a heavy base so the key does not slide around. If you
cannot mount it to something substantial, set it on something that will help
keep it stationary, like a mouse pad or a thin piece of rubber.
Setting up a key is a matter of personal preference, but if you start with the basics
of having a small gap, loose spring and tightened down screws it will give
you a good start. If you start with a bigger gap it may seem easier, but
you will probably want to reduce the gap as you get more proficient, so you
may as well start out with good habits and not have to retrain your motor
memory later.