SS870 upper float switch in waste tank appears to be intermittent. Symptom: engine runs smoothly, hesitates for a second or two (engine dies), then resumes immediately at full RPM while tools are operating. Anyone know how to clean/maintain &/or adjust the float switch? Its a Harwil L-21N. A couple years ago a great mechanic at Hi-Press in Tulsa adjusted same switch in my brother's SS870 but I'm 900 miles from Tulsa with no Sapphire TM tech close. It's a magnetically actuated cherry switch in a waterproof housing, very cool engineering. Just can't figure out what he did.