How much free play should there be in the central axis (the "scissor thing") in the window regulator?

My windows have insane leaks - I've installed new seals, so my current suspect is free play in the regulators. The passenger side window is especially bad; it moves about 1-2 cm back and forth and 0.5-1 cm vertically. Does anyone have properly sealed windows & know how the regulators _should_ work?

Also, any ideas on tightening the rivet would be welcome.

 

Are you sure the back and forth movement isn't just due to worn out window guides? The window regulators themselves rarely go bad.

 

Dumb question - do you mean the plastic roller wheels, the metallic C-shaped tracks they move in, or the cushioned rail on the hinge side of the door?

I did notice that this circled pin in the "regulator cam" (38), that has one of the plastic rollers at the end, is very loosely attached to the regulator cam itself, so that might explain the window's movement. I got another one from eBay where the pin is properly fastened, so that part is going in at least.

I also have "new" regulators from eBay that have less free play than my original ones, but they're otherwise crappier (rusty, one of the rollers is broken, etc). In that clip above the 1st regulator is from eBay, the 2nd one is my original part.

 

I meant the cushioned rail on the hinge side of the door. That's usually the first thing I look at if a window has play in it. You can see the part I'm talking about in this eBay auction. http://www.ebay.com/itm/1985-Chevrol...9Xf~GT&vxp=mtr