I recently purchased a non-genuine KAD style quick shift from ebay for around £20 and encountered the following problems:

mounting it was incredibly difficult it did not sit very well on the top and required screwing in rather than the drift pins (not a good sign)

the nylon ball was the incorrect size (so I nitially used the ball of my old gear stick)

the circle clips were weak and the bottom one broke causing the ball to drop and cause the gears to jam intermittentkly and gear change to become near impossible

I then filed down the new ball to fit

this was better but the fit was still VERY poor

the gear stick now often jams and grinds my gearbox renderingit utterly useless

I am now returning to my old gear stick as soon as I can but I may well have to get a new gear box which is not going to be cheap.

I am not the only person to have experienced such problems

RESULT if you are going to get a gear shift do NOT buy a cheap chinese copy from ebay unless you are:

prepared to spend a lot of time getting ti to fit properly for it not to fit very well even in the end

prepared to buy a new gear box AND gear stick at a later date

OR

stupid

BUYER BEWARE