[watahyahknow]

if you know someone with a small lathe he might be able to make some new (oversized) bushes from a piece of bronze round stock or maybe a carbshop has the bushes you need .
if you have them made make the outside slightly oversize and the inside slightly undersize .
you ream out the holes in the carb where the trottle shaft goes through front to back so everything is alighned again then push in de new bushings maybe heat the carb on a stove to make the aloy expand a little and you should be able to push them in , let everything cool and then ream the inside to exactly the size needed allso through and through , this should fix the problem ..... oil the bronze before you put them in by closing the bottom fil it up with light oil put youre finger on top and press the bronze is a bit open and the oil goes in the pores of the material

it might be that the trottle shaft is bent causing the exessive wear