if the contactor is moving slowly even when you disconnect the control wire/lead manually, you have a mechanical bind in the contactor. loosen all the screws that hold the contactor together and see if you can 'reseat' the assembly to sit correctly. if it still does it, disassemble the contactor assembly and inspect the plastic and bakalite pieces, as well as the armature, and maybe swap the moving tips from one side to the other.