Wooden screws can sometimes be impossible.
Its sad, but its a fact.
   All I can suggest is to add a lubricant and "rock it".
In times of really bad stuck I have even resorted to ordinary 
lubricating oil.
Same 10wt I use to lube practically everything.
   Hold it up so it can soak into the treads and pump some in.

Start twisting back and forth. Trying to force big movements anywhere 
seldom pays off.
So rock it back and forth. You'll get a bit of movement.
  Capitalize on that movement. Keep working it in the sweet spot and it 
will begin to move a tiny bit further each stroke. Just keep rocking it. 
Adding lube occasionally.
Don't get greedy or it'll stick again. Keep rocking.
  Sometimes you have to rock it all the way off.
     yours scott



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*******************************
    Scott Grandstaff
    Box 409 Happy Camp, Ca  96039
    scottg@s...
    http://www.snowcrest.net/kitty/sgrandstaff/
    http://www.snowcrest.net/kitty/hpages/index.html