I 3D printed a small block to test the size and after a bit of filing it fitted but an odd problem popped up.
Moving the lever towards me moves the needle to the right, move the lever away and sometimes it moves to the left and sometimes to the right?
Move the lever very slightly to the rear and the needle moves left for 0.2mm or 0.3mm (it varies) then the needle jumps and starts moving to the right?
Broken spring or something overshooting? Its not that old but a cheapy one. Contacted the seller and hoping they will exchange it.
Probably need to look for a better one. Proper brand 
I still need a better holder though, if they do replace it the holder is likely to be just as rubbish.
X$M brand.