52 Super C Temperature Gauge Won't Work

[TNSuperC]

I see the wire running from the right-front of the engine back to the gauge. The wire doesn't appear to be broken. How do I determine if the sending unit or the gauge is the issue?

 

[MIKE R]

Is it a wire or a capillary tube. They do get old and stop working. Not hard to change out with a new one.

 

[TNSuperC]

The inner tube is wrapped with a helix of metal (looks like a big long spring), so I guess that is a capillary tube. Looks like I'll have to remove the battery-box/battery to get to the gauge.