If the wiring at the site was recently upgraded and there were no previous issues with the inverter then I'd start with some basic diagnostics of the power source.
The Lippert slides are very simple: motor, ram, cog rail, bell-stop, and jack plates. Many of us have adjusted our own slides, so I'd be suspect of any dealer who can't figure out the adjustment and is creating a reoccurring slide issue. Just a thought, call Crossroads and either find an independent repair shop or another dealer through them.
2013 Jayco Eagle 334RBTS
Crossroads Forum Lurker