Reverse lights dead

[Drag0na5h]

I had this problem for over a year now and I don't know why I didn't do anything about it yet. Anyways my back up lights don't come on when I put my car into reverse. The bulbs are still fine, in fact I changed them and tried again but still no light. Sometimes after driving my car for a while and I reverse, the lights will actually come on but I kinda have to push up on my selector lever while it's in "R." It's an automatic by the way. Then it comes on, but when I stop pushing it, it goes off for a while and then lights up again but this time stays on. I am not sure if it's a mechanical failure, I'm leaning more towards an electrical failure but I don't know where to start looking. About two years ago I had the problem with my brake light failure warning light on the dash staying on and when that came on my taillights wouldn't light. So I did the mod where you cut a purple wire on the brake light failure relay behind the driver side taillight and the problem was fixed. But then that's when my taillights started to not work anymore. Anyone experience the same problem? Maybe I need that purple wire for my taillights? I have no idea.