The pumps are Mayfair Marine 1000 GPH (at least the one's I've looked at are) and are made of a black pump inside a yellow casing. The pump can be removed from the casing with a twist if you need to place.
Its possible these are not the stock pumps but I thought they were.
The front ballast system was "upgraded" (I was told) to a 600 lb center bag. Maybe that included replacing the pumps with 1000 GPH ones.
And maybe the others were upgraded too??
I know if I had 500 GPH pumps (or even 750's), I'd want to upgrade to 1000!
I did a lot of flipping switches, but nothing worked. Maybe I need to follow the pattern you mentioned above.
I really though I had read these were "lock proof" pumps.