I've just been giving a recently purchased a September 2008 manufactured Revo a clean and service and came across an interesing thing inside the rudder drum.
There is a small spring-loaded cam that appears to retracts when the rudder "Up' line is pulled:
I haven't seen it inside any of the other rudders I've removed. I can't see it mentioned in any of the offical (current) Hobie manuals or rudder installation instructions, so I'm guessing it was something that was obsoleted?
The Revo has the T-handle rudder up/down mechanism and click-n-go drive mounts, so it's one of the first '2009' models. Is this somethign that was used on the older model twist-n-stow rudders?