Folks here is what I read
Charge one (Of the two 12 volt batteries in series) Then the other.
Or you could remove them re-wire in parallel and charge 'em both together. then re-wire in series to operate (Did that in fact).
You said "but will not charge from the plug on the column."
Which column? If you mean the park's 20 amp outlet.. Might be disconnected inside the box (Use a 3-light tester to insure it has power) (you should be using one of those on the RV every time you plug in).
If there is a socket on the control column on the scooter that you are supposed to plug into.. Check to see if there is also a socket on the battery box.
You might also want to volt-meter the charger (50 volt range on the meter if you choose or auto-range if it does that).
Possible the charger is kaput.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times