Hi "Bub"
As you just previously brought the motorhome , why not make contact with the previous owner (or dealer) as to the operation of the panel and changes that may have been made to same. This is common factor on old motorhomes where faults occurs
Hopefully they will inform you as to exactly and why the changes were done to the panel and it's operation , before you attempt any changes or repair yourself. Stops all the guessing and gives you a heads up should you wish to repair or not
Regarding the manual , who knows they may even have a sheet or two of same, (They may just have to look for it,one never knows )
Regards