The 8-ways are the same as the 4-ways with the exception of the round holes on the 8-ways, and a larger actuator on the 8-ways.
In addition to the above question about whether your sticks are actually 4-ways, the other three things I would check are:
1) Is the actuator round?
The actuators on both types of stick are basically a straight-sided sleeve over the joystick shaft.
The 8-way is a little larger than the 4-way.
You are saying that there is a "larger side" on the actuator, and there shouldn't be.
2) Are the leaf switches adjusted properly?
The inside leaf should be almost, or actually, touching the actuator.
The outside leaf should be almost touching the inside leaf when the stick is centered.
That allows very slight movement to make the leaf switches close.
You can actually adjust the 4-ways to allow diagonal movement if you bend the leaf switches close enough to the actuator.
The best way I've found for adjusting the leafs on the switches is to use needle-nosed pliers, grip the leaf very near where it connects to the base, and twist lightly on the leaf to get it where you need it.
I actually use the bent-tip type pliers because these make it a little easier to make adjustments lightly enough.
3) Are the grommets ripped?
A ripped grommet will usually not make the stick quit functioning, but will make it easier to move in one direction because there is no resistance from the rubber.
As far as the grommets go, the $24.50 price on them seems to be the norm at the moment.
Considering that you can get NOS sticks at $25.00 ea. this price isn't bad if all you need are the grommets.
If you need the leaf switches too, it is probably cheaper to pick up complete NOS sticks.