valve and cam chain adjusment help!!!!!eekkk i broke it!!!!!

[always3never4]

http://www.3wheeler.org/dirtwheels/06-87~pg74tuneup.jpg
ok so im adjuting my valves but i cant get the one part off
its the part where the arrow is pointing at in the middle bottom pic
its so tight it wont unscrew...it started to strip so i stoped and decided id ask before i messed it up to bad
i need help plz!!!!!!

[Somekindofjerk]

Spray some pb blaster or other penetrating oil over it and let it sit for at least a half hour and then go out and but the screwdriver on it and tap it with a hammer then try turning it out.

[350x'inNY]

Maybe try an impact wrench? But then again, it's soft aluminum. I've also used a nickel and a pair of vice grips too.

To eleveate that problem on my 350X's I've replaced the OEM original ones with later model OEM ones off golf carts that have a 5 or 6mm hex head.

Bruce