Does not look like there a place for a center board or swing keel.----Cabin sole look like fixed keel to me.----And I have sailed on many different boats.----From a Laser to 62 foot ( 55,000 lb ) go anywhere in the world type of boat.
I would say the voltage should rise right away.----It does on other motor brands.----Have you considered getting a pair of different motors.----Seems there are a lot of issues.
A very common event if you have worked on more than 1 of these wonderful 6 HP motors.----Picked one up for cheap last year.----Broken tip on the needle is why it was discarded.
????----The pump is driven by CRANKCASE compression and not cylinder compression !!----Your motor has 2 separate crankcases.-----Do some proper trouble shooting .----Do not make assumption on how your motor works !-----Your motor can run on one cylinder and sound normal to an untrained ear.
The electrical bits on the pump are for the " no oil " warning system.-----The pump has an air motor driven by crankcase compression.----What is your motor doing / not doing ?
See post #2 on this.---Based on the wiring it is a 1995 or older !!----Some will argue.----These motor often suffer from broken piston rings.----I do not have enuff fingers and toes to count how many engines have failed because of that fact.
I remember a knock on the door years ago.-----I was on a " party line" with a few other folks.-----I was asked whether my phone was in order.-----Folks heard a dog barking on their phone.----My dog let them know it was my phone upsetting the system.----Somewhat embarrassing.
