Surge Guard 40250-RVC and 40350-RVC are interchangeable. Buzzing usually means loose connections - tighten all terminals. If buzzing persists with tight connections, the relay may be failing and unit needs replacement.
Triple E built quality coaches in Canada. At 24 years old, focus on this specific units condition rather than brand reputation. Critical inspection points: water damage, engine hours, service history, roof seals. Get professional NRVIA inspection before buying.
If Lippert no longer carries the 10540 controller, you have several options: find compatible aftermarket controllers, upgrade to newer Lippert systems, or locate refurbished units from RV salvage yards. Many newer Lippert controllers are backward compatible.
Intellitec BD-0 latching relay typically near battery compartment or in adjacent electrical bay. Look for box with heavy gauge wires. Trace wires from disconnect switch if location unclear. May need to remove panels for access.
The front run bay control panel #166-2011 for your 1999 Monaco LaPalma is a discontinued OEM part, but several sources still carry new and refurbished units. You'll need to verify compatibility with your F53 chassis electrical system before installation.