I have an 2001 Marquis Destiny spa. Recently we just drained and refilled the spa. Upon restarting the spa the motor directly beneath the control box rapidly begins to turn on and off. It almost sounds as if there is some type of air cavitation happening. When the spa is run at "high speed" the motor runs smooth without any hesitation and there is good pressure at the jets. I checked the engine looking for a bleeder to let out any air and could not find one. Can you give me a recommendation as to how I can fix the problem or if this may be a common occurrence and what I would need to do to fix it.

I have also found the joints on either side of the heater have slight leaks when the motor is trying to start and when the running at full speed. When the power is off the joints do not leak. Any suggestions as this again leads me to believe there is air causing excessive pressure in that area of the system. Any sealant suggestions?

Thank you in advance..