Whew.  For a second there I thought I was gonna have to retire and only fly ARFs.  I read your posting and ran to my shop to check.  Its been awhile since I last looked so I couldnt remember.  Thankfully the answer is yes, I can see all the way thru and there are no set screws.  As far as I can tell it is threaded all the way thru.  I can turn it in from both sides, but only about halfway.  I cannot see any obstructions.