What atomizer are you using?
As Manni and dspin said, the brass button pin you got is not compatible with your button (hexgonal head), the brass pin is only for the Adjustable Throw Buttons.
Probably your GGTS (because the serial number) has already a brass button pin (nickel plated). One of my ss GGTS (serial number 1183) came with hexagonal button and it had brass nickel plated button pin, I discovered it because I was sanding a little the button pin to remove black spots on the connection point, while sanding it, the nickel plated was removed.
Also that could apply to the pin screw of the fuse kit (on the first batches of fuse kits, the screw is nickel plated brass), probably you will have better results using the brass axis post with the brass battery spring. Of course, you can remove the brass battery spring and install the top part of your fuse kit (the black derlin with the screw), so you will have a brass fuse kit.
Newer fuse kits came with one brass insider spring, you will have better results by installing a second fuse kit spring for a total of two springs inside the fuse kit.
I think the short is not on the button assembly, because button only closes the circuit. Check the positive auto adjustable pin assembly, there are little o-rings inside.
Also, a common problem is with atomizer's center pin and the GGTS's auto adjusable positive pin, if you tight too much the GGTS, the positive pin could push up too much the atomizer's positive pin, causing it to short circuit.
How are you connecting your atomizer to the GGTS? Another common problem is when using Chinese adapters arrays on the GGTS, to connect 510 big atomizers instead the GGTS original adapter, those adapters meant to be used with the GGTS's auto adjustable center pin system, so they short circuit very easily.
You can try by removing (of course in case you are using them) all the Chinese adapters, the GGTS's collector tank and connect the atomizer directly on the GGTS connector, and do not tight too much the GGTS.