Reverse light works when it wants to

[Cruz]

I have a new switch fitted so it isn't that.

I parked up to a shop window so I could see what was happening and found that my reverse lights only work when they feel like it.

It all seems to stem from how I throw the gearstick into reverse and they work depending on how much I pressed the stick down and how far I threw it to the left and differing variations of former etc etc. All rather random

Is it something inside the gearbox that isn't right and isn't depressing the switch or is it something to do with the linkage or gearstick end??