On your Journey its the same source, an HWH system, for your slides and levelers. One common tank for the hydraulic fluid and a common system of pumps etc.
Try going to a Freightliner shop that handles RVs. They can diagnose and repair. My local one did similar work for me (locating/fixing leak on a leveler hose line.)
2004 Winnebago Vectra 40KD
Roadmaster Tow Dolly