Melex Model 666 wiring schematic needed

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I have just purchased a Melex model 666 cart. It has two bench seats and a small diamond plate pickup bed in the rear. Am just starting to find out information to repair it. It looks like the wiring under the front seat has a component missing. I would guess it is a solenoid from first look. The cart is 48 volt and has a GE motor. I think I can read 2.8hp on it. The serial number on the cart says model 666 serial number 600305. Don't know what year. It does have a Curtis 1204-402 motor control and a Lestronic II charger wired into it. I got it Air Force surplus, looks to have been used on base in Arizona.
Any info or help in finding wiring info would be greatly appreciated.