What Bob D. says and if you know you can do it, modify the wiring layout to better access the vent plugs for ease of maintenance. I myself would look at turning the batteries 180 degrees, but you have to know how to properly reconnect them.
And while the batteries are out a good cleaning can be done and a proper recce for any hidden fuses or such that may be under there.
Good luck!
Oh, and always remember, Negative off first and connected LAST.
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