How do I set my Dual Fulcrum vibrato for backward bends?

HI,
I have an S-500 that is truly great in every way. What I can't figure out however is how to setup the Dual Fulcrum vibrato so that it readily allows me to reverse bend (backward bend) the vibrato arm such that the strings go slightly sharp. Right now I run a mixed set (heavy bottom light top) set of strings with three springs on the vibrato. I am assuming that I ought to change to 9's and perhaps two springs holding the vibrato but in general the vibrato bridge tends to simply unload when you bend it backward in a clunky sort of way rather than bending backward smoothly. Can anyone give me any advice on how to get the vibrato arm/bridge to bend backward smoothly and responsively. Thanks in advance.

When set-up properly (with the tension between the strings and the springs balanced and the bridge set approx. 3/16" above the body) you will be able to bend up or down. The gauge of strings shouldn't matter once everything is dialed in.

Here's some set-up instructions:
http://www.guitarsbyleo.com/GALLERY2/main.php?g2_itemId=386

It sounds like someone tightened the trem claw screws to maybe compensate for only having two springs. You might want to add a third spring (especially if you like heavier gauge strings) and I bet you'll find the trem claw screws will need to be brought out a little to find the right balance point in tension.