ok, you have 2 options, the first may, or may not work with the older swinger. go down to lowes, or annother store and pickup a 7" long 1/2" bolt. it will fit in the carrier, but you will have to use 2 12mm hard washers on the head, and cut half the threads off. pair it with the shoulder nut. leave it loose and see if the axle stays strait. if the bolt doesn't go in, or is too sloppy, they have some brass bushings that you can replace the welded ones with on the swinger at lowes. or you could just grind the steel ones. or, probably easier and you should try first, leave the top and bottom bolts loose, pull the axle back so that it is square and the chain is adjusted, then turn the adjusters so that they just touch. lock the top and bottom bolts down, tighten each adjuster the same, so that there is just a little pressure, then lock the lock nuts.