The PO in mine did something that seemed to work a little bit, instead of shoulder bolts, he put in the next size bigger and longer bolt with two nuts jambed against each other (if you cranked the nut to the bolt then there is too much stress on the open close mechanism. I'm not at the shop, so can't look - just guessing but the original 3/8 shoulder bolt is in a 7/16 hole (either that or mine was just worn in a near perfect 7/16 circle) - so upping to 7/16 took the slop out there.
But that is just guessing a bit - what is causing your slop, the springs worn / broken, are you getting slop on the top bolt, bottom bolt, is the firewal flexing and causing slop on the bottom half (you said bushing so threw out the above).
I think he's talking about the permanent pins that hold the arms together. Not the springs or the bolts going through the cab itself. I have heard of people taking those things off and hammering the crap out of the backside of the pins in order to make them flatten out and fill up the worn holes better. BUT, if you go too far, you might just lock up your mechanism. I would be afraid to do it, but I have heard of some folks doing it that way.