Actually, Jim, I just punched the wire into the TE of the surface and used the tubing to mark the 5" point on the wire.
IMG had some drawbacks, too.
a) The plane has to be on a really stable surface with room to set up the gauge. That might end up being a really big surface for a sizeable plane.
b) Accuracy and repeatability depends a lot on the ability of the user to place the gauge arc exactly 5" from the hinge line.
c) Modern aerobatic craft may have surfaces so large that 5" isn't enough.
d) Parallax from wire to gauge.
e) The two wooden rods supporting the gauge always seem to be too long or too short.
f) The clip holding the gauge plate onto the dowel often interferes with the wire.
g) Wind is a problem.
I'm sure there are more issues with IMG I've forgotten since I went to the Hanger 9. IMG is a PITA, but the battery never runs down.