The originals have 8-way sticks in them that have no corners, so I would suspect they are probably Wicos.
The seller mentioned above is a GREAT guy to deal with.
I've bought alot of stuff from him, and EVERY transaction has been perfect.
He has alot of the 4-ways at the moment, and has been using some of them to build 8-ways when he can get good bodies for them.
He replaces everything on the 8-way except the body and the actuator.
You might want to check with Oscar, to see if the stick in that machine is supposed to be a Wico.
If so, check yours out.
If the body is still in good shape, you could buy one of the 4-ways from Nicade, and replace all the trouble parts in yours (grommet, leaf switches, etc...) with the stuff from the 4-way, keeping your original actuator, stick and base.
I can't think of anything that would make the stick hard to move, if it is a Wico, though.
The two biggest problems Wicos have are the rubber grommet ripping, which lets the stick move too easily in one direction, and the leaf switches bending.
Is the stick hard to move ANYWHERE, or is it just hard to get it to make contact with the switches?
If it's just hard to make contact with the switches, they may just need to be bent back in toward the center.