Flickering reverse light

My reverse lights flicker and they often randomly stop working for a while. Tried to replace the lights, then the reverse switch on the gearbox... Still not working
Since they still blink its not a fuse problem

Anyone had this problem before?? Plz HELP!
 
Mine recently stopped working altogether, I replaced the switch on the gearbox on the weekend and is perfect now. I found the old switch had a high contact resistance.