Ok I broke a radius arm on my EXI 450.My frame is a pro carbon style but my head is not,I ordered a set of radius arms thinking its a pro and they are bigger than the ones on my chopper and look to have bigger mounting hole.Mine are installed with one self tapping screw going into the plastic arm.What do I have? I thought I seen this sight showing service manuals for many different helies but I do not see any forums for them, am I missing something?