IBM to Apple II joystick cable

[grover@emunix.emich.edu (Grover Thomas)]

     I checked out a few FTP sites, but I couldn't find any info on
this, so I'm asking here.  After remembering those dual 'Apple II
-or- IBM' joysticks of a few years back (the ones with the awkward
cords with both a D-9 and DB-15 connector), I was trying to help a
Bimmer by creating a small cable to wire my (Apple II) CH Products
Mach III joystick into his IBM joystick port.
     I got the paddle connections (X and Y motion) okay, but the
buttons are proving to be difficult.  Instead of pressing them down
to respond, I have to hold them down and release them up to shoot.
This leads me to believe there is more than a 15-pin connector that
differentiates an Apple stick from an IBM stick.

     Am I missing some vital info about the inner workings of the
Apple II joystick?   Are the switches normally closed?   Am I insane
to try this?

     If anyone has done anything like this before, or can point me
in the right direction (without destroying my trusty Mach III) I'd
certainly like to hear from you.

-- 
Grover Thomas       grover@emunix.emich.edu   (Nifty quotes currently down)