Has anyone else noticed these mounts being loose?  I verified that mine is sliding on all the way, but it's fairly loose, and in fact the GPS actually fell off the panel and into my lap during a fairly rough attempt at a hot start.  I have it in portrait mode, which makes it worse, but I don't really have much confidence in the mounting security. 
I've got a VBox Sport (automotive GPS datalogger) with the same "Richter" mount, and it fits really tight.  I tested the RAM mount from iFly with the VBox GPS, and it was also really tight. In fact, it was so tight I never pushed it hard enough to get it to snap in place.  That would make me think maybe the slots in the back of the 740b are a little larger than ideal.  Next time I'm at the hangar, I'll try to remember to try the 740b with the VBox mount to see if that's loose also. 
Rusty