Yamaha 2006 F250 four stroke

Not charging batteries. Boat in remote location Mexico. I suspect rectifier? can I change out myself, no service available in area. Long haul back to USA?
When I hook up meter, no amp output. Actually loses when rpm raised.Motor electronics usng the battery power?

What parts should I take.O rings, gaskets ?

Also broke oil sensor by filter when changing filter. Plug on harness OK, is sensor a screw out' put new in deal?
Appreciate any input

[boats.net]

The regulator is basically simple to replace and oil pressure sensor is threaded. Shouldn't have any problems.