Note that the number of turns of the wire at the ampere meter needs to be tested. Measure with a reliable amp meter to compare, first with small draw like with the light, and with a large draw like adding the horn. The largest disparity btw. one or two turns is likely to show at small amperages.
And the direction of the loops may be turned in order to shift the direction the needle is pointing. The tightness of the loops or thickness of the isolation on the wires has nothing to do with the magnetic force the wires is making. The difference is in the meter.
The meter pointer is of silver and thin as a hair, so it gets damaged by just thinking about it! and the needle pivot points can/will rust. Nothing that a proper watch maker can't fix easily. But the main problem is that the U shaped wafer thin magnet at the bottom of the cup does rust and that makes it expand and break in time. The isolation under the magnet is of wax paper but it also swell in water and in time. The bottom nuts can easily be overtightened. All that contribute to the magnet breaks in pieces.
The meter is basicly simple but contains of a few presicion parts that has to work. Water is the main enemy. If anyone has a source for the thin magnet, I am interested to buy.
