Are your recovery tank filters clean?if so it could be the vac motors and or bearings.If twin vac machine try 1 vac at a time to find out which or maybe both vacs are duff.over period of time warm moist air does affect motors and bearings,making them whine when under load. if motor duff try Woodbridge commercial for the bits.
sparky col.
February 2009
howtomendit.com for free repair help, information and advice.
