Humming from Progressive Industires EMS 50 amp system

After you go through all the suggested regiments about cleaning the contacts to reduce the hum they will likely send you new contactor assembly. This will require you to disassemble and reinstall the new one. I hope it's in a convenient spot. When I reinstalled mine in our new rig I put plugs on each end to make it easier to remove and handle any future repairs if necessary.