We performed a comprehensive mechanical repair and system diagnostic on a residential hot tub in Carlsbad. Our team inspected the internal components, including the NPI control box and electric pump, to address heating performance issues. We identified significant corrosion on the heater bus bars and localized leaks at the plumbing unions. We replaced worn silicone gaskets and seals to restore watertight integrity to the plumbing assembly. After installing a new Balboa Water Group 4.0kW heater, we verified the electrical draw using a digital clamp meter to ensure safe operation. We also measured and replaced the pleated filter cartridge to optimize water flow and clarity for the spa.