F*****g flat 4 shifter

anyone on here had any experience with flat4 shifters like the ones Machine 7 sell?? im not implying they are crap coz when its working fine i love it but ive been having real probs with selecting reverse and it seems to work itself loose a few days after its been tightened.

It hasnt got a button for reverse and you dont have to push it down which means that sometimes when i go to select second gear when approaching a juction it slips into reverse, how do i stop this??