I've never seen this before but I can give you a little info that you may or may not already know. When you first turn on the machine the carriage lifts to its highest point. That is why the heads are always uncapped when you first turn the machine on. I would inspect the connections around the worm screw that regulates the carriage height. I'm not exactly sure what drives this system but I believe it uses air pressure. If you've ever turned the machine off when in maintenance position you would notice it falling slowly as if its losing air pressure. Check for an air line to inspect as well as any other electrical connection such as possibly a solenoid which would regulate the air pressure.