So what exactly makes these knock offs so bad!? Have you actually tried them? A leaf-switch is a leaf-switch, they all feel the same. I've owned an original robotron for almost 8 years now, and when the wico's went, I replaced them with a similar looking one as linked to above, and they feel EXACTLY THE SAME. I still have the original wico's and could probably transplant the leaf switches, but thats what broke and decided I'd just replace the entire stick. I did keep the original handels installed as they are slightly taller than the chinese knockoffs.
A leaf switch is more or less a leaf switch, true. As long as it makes contact, it's doing it's job, unless you've got a stick that uses the switches for resistance, like an original Galaga stick. The difference isn't in the switches, but the construction of the rest of the joystick.
There's more than one knock-off variety floating around out there. The only one of those knock-off sticks I've got has a different diameter shaft than the original Wico sticks, so the handles could not be transplanted from one to the other; therefore you must have a different stick from me. After some research, I believe the one sold by Centsible amusements is probably the same as yours, not mine, as other users have reported being able to swap shafts between true Wicos and the Centsible stick.
Both knock-off versions I have seen do have a grommet in them, but it's not the SAME grommet. On mine, the knock-off grommet's hole is not perfectly fit to the handle, which lets the handle slop around some before you actually start to flex the grommet. Other users have reported the same trouble when doing a handle swap with the other version.
Aside from the different grommet, if you have a look at the restrictors on the top and bottom of the joystick base assembly, you'll see that the knock-off makers somehow managed to use 4-way diamond shaped restrictors, and then equipped the stick with an actuator that still hits the diagonals. This means that you've got an 8-way stick without the smooth, round action you'd get from a real Wico 8-way. At the same time, you've got the FEEL of a properly restricted 4-way, but can still hit the diagonals, so the stick will still suffer from the typical using-an-8-way-in-a-4-way-game problems.
Do a search for "Wico Knock Off"; you'll see lots of other talk about these issues.