Picture this; the gears are gnashed together hard - lots of tension and pressure on them. Then this little electric solenoid give it a little pull. Yeah, nothing is going to happen. That solenoid just isn't strong enough.
So letting off on all that tension by either backing slightly or just letting the truck coast releases all that pressure and the wimpy solenoid can do its job.
I prefer the old style lever for XFER case duties. If it doesn't come out of gear, the the only weak link to blame is the guy pulling on it.
