Help With Sun Test Meter

I know there is a wealth of knowledge on this forum, so perhaps someone can help me out a bit on something besides my KZ-1000. While surfing the net for Kawi parts I came across a used Sun Electronics TDT-11 Tach and Dwell meter. The meter looked in really good shape as these haven't been made for generations, but the seller didn't know if it worked or not. Well true to my nature I took a chance or it working and bought it. While it functions, it isn't very accurate and I can't calibrate the dwell meter. I used Sun meters years ago when I worked in a car dealership turning wrenches so I am aware of the steps needed to operate these. It does use two different types of batteries and they are brand new. My question is, does anyone know of a source of repair for these meters today? I checked around on the internet and so far came up blank. Thanks for any help in advance.
Rick H.

I realize this is an old post, but in case you are still working on it...

I just wanted to make sure you are testing this on a classic car with a distributor, and not a Kz, correct?

One coil of a Kz ignition system, electrically, won't register properly on a dwell meter designed to measure distributor degrees on a classic car. The Kz fires once per crank rev, whereas the dwell meter expects the coil to fire once for every cylinder for every two crank revolutions.

In addition to that, the Kz dwell is specified in crank degrees whereas classic car dwell is usually distributor degrees which is the same as cam degrees.

So to get the correct dwell reading in crank degrees for the Kz, you have to multiply the dwell meter's 4-cyl scale reading by 4.

Example: Set the knob to 4cyl mode. If the reading for one coil of an inline-four Kz is 45 degrees on the 4cyl scale of the tester, then multiply that by 4 to get 180 crankshaft-degrees of dwell.

Likewise, the RPM reading with knob in 4cyl-mode needs to be multiplied by 2 to get the correct RPM of the Kz.