The touch point is made of a brass insert with two insulators, two lugs and a nut. The two lugs are used for the electrical connection to the PCB. These have a specific way around they need to be.

If you read the battery voltage from the Touch Port as a negative,

the touch port wires are probably the wrong way around. This is also the most comment cause a fault in the baton with wires being broken off after the unit is opened.

If the touch port is dirty or corroded it will not make proper electrical contact. This can be cleaned with a damp cloth or wire brush. The inside of the touch port can also have foreign matter in which would result in a short to the touch port.

Older units have springs this is normally removed as part of a service and replaced with wires

There have been some improvments to the touch port assembly. The bottom Top hat has been replaced to make the unit more water proof. It has been replaced by a fiber washer, an o-ring and some heatshrink. The fiber washer can also be used as a spacer depending on the casing you have. Add more washers as needed. The Oring forms a better seal than the top hat. The heat shrink to to help prevent shorting. Make sure you do not cut more than 2mm of heatshrink.