I recently got this meter from another GreenKeyer. I bought a plastic electrical box to mount it above my workbench to work on TU's.

It turned out to be a perhaps 1 mil movement. Fortunately I have a small roll of resistance wire to make shunts.

It usually takes about a foot of it  to turn a 1 mil meter into a 100 mil meter. That has to be adjusted in 1/4 inch   increments to calibrate the meter. This one only needed about 4 inches of wire adjusted in 1/16 inch increments.

It was a stinker, but I finally got it. In the photo it is in a 60 mil loop. I use two 3-circuit jacks so I can connect a TU to one jack and come out the other to one of my loops to actually test with a Teletype.

I expect that meter to come in very handy. The green marking will make it very easy to set the loop current.

Tom  N3CRK