not quite 100% sure what you're referring to, but if it's the screw that goes into the carb to hold the bracket on, I think you can just get some small vise grips and put them around the outside of the head of the screw and slowly turn it loose and then replace it. replace it with a hex head screw now instead of the soft phillips head oem ones. the throttle cables were the biggest pia's for me too when i modded my carb. my throttle still won't snap back and sticks like a 35 year old bike, it's real aggravating. other than that, while you have it off you also may want to add one of them adjustable air/fuel screws that some are putting on. i can't remember the brand but it lets you adjust your a/f screw after you rejet it in case you don't get it set right. you can just screw the T-screw that you replaced the air/fuel screw with. it hangs down under the carb.

i'm gonna take my bike in for warranty work to fix the throttle and find out why my rear brake will hardly work. this April i'll have to do it since the warranty is up around the middle of that month. don't give up on that carb, it's a real pain but it's really not that hard once you look at how it came out and where all the hoses go. also, make sure you did all of the carb mods. while you have it out, you should do the crankcase breather mod. do it with a torch and a set of vise grips holding a drill bit of the right size and it takes all of 10 seconds and there's no mess. of course, then you'll want a hi-flo air filter like twin air or Uni-filter. good luck. the payoff is real nice.