Doubling Your Brake Lights
 

Fitting: -
Gain access to your bulb holder, some instructions are here

use a lighter or as I did a cooker lighter to heat up the marked plastic weld, this literally only needs passing into the flame 2-3 times and removed quickly.....this softens the plastic enough to then use a long nose plier to squash the flattened plastic back into a raised button.

Whilst the plastic A. is still warm lift the contact B. to allow access to the hole it was sitting in.

You can then drop the previously extracted spring contact into the hole and seat the pincing blade part into the hole base as shown.

The raised contact can then be pushed into the slot and at the same time the melted plastic button is pushed through the contact hole.

After applying some additional pressure on the contact strip to help return it to its original seat, the plastic button should be gently heated again with a few flame passes then the pliers used to apply pressure on it to flatten it and return it to its holding form.

Simply check the contact for proximity to other metal and adjust it to match the spring height of the original contact beside it.
And that's it, refit the bulb holders.

Both bulb holders will work as designed, 2 sidelights and 2 brake lights will illuminate in each cluster.