Dinsmore Compass
 

I have a mirror mounted Dinsmore auto compass, it was always off a bit. it has two adjustments screws, one in front and one on the side. The ide on seemed broken, so I took the unit apart and all that was wrong was that the adjustment bar slipped off the mount.

The two bard have to small brass rods that affect small changes in magnetic field. once I put them in the cradles and closed up the unit it read better.

Once it was remounted, you have to used a NON-METALLIC (plastic) small screwdriver to make the fine adjustments. You can only do this once its mounts as the cab metal do tend to throw off the true north. I used my cell phone compass the check.

I did not know if any one has seen the insides of one of these compasses.

Re: Dinsmore Compass
 

I don't believed the rod is brass. It should be some kind of ferrous metal. They use a similar arrangement in aircraft standby compass, their adjustment screw are both on the face of the compass and covered with a correction card. We use a brass screwdriver to adjust them.