Prentice when you are sitting on the lift and in neutral and turn on the key, do you hear a contactor close? It seems the lift isn't recognizing a closed contactor or contactor isn't working. You mentioned lift would move slow in initial description. I would check r-b contactor tips and associated bus bars along with brushes. Have seen where electrolytes have boiled over and effected a diode beneath battery. This is true also of units used in application of freezers where the docks/charging area have poor moister control. These can be recognized by a faint beep of the b-u alarm