Gilera runner fx rear brake

I have tried to tighten the rear drum on my runner and the nut wont move its just starts twisting everyfing and i dont want to snap it so i cant put to much effort is there an easy way to losen it? any help is appreciated

 

just put wd40 on it and leave it over night and then try it and tap it as your turning it

 

yeah clean both the threads from the bolt and nut

undo the trans case and put a clutch tool on the clutch bell

I have a brand new 41mm buzzetti one if you want, bought it for my nitro but wrong size

 

i was finking of replacing the brake cable and was wondering if one for a typhoon 125 or if any other bike will fit as i cant find a brake cable to fit a runner 125 also would it cum with the nuts you use to tighten it?