Starter motor sticking on flywheel - Had the wrong bendix on. Thing to check is the number of teeth.
The one that was sticking had one less and it only jammed occasionally.

Starter motor not working - First off, check it’s not jammed but if not, the solenoid may need changing. There is a way of testing this but involves using jump leads to feed power direct to the starter motor but nothing I could advocate unless carried out by a professional mechanic. The mechanic can even test the solenoid by using a jump lead to connect the two solenoid terminals briefly which can indicate ignition switch problems etc.

Engine cutting out - Obviously there are numerous potential causes but having an engine running fine which then cuts out or splutters occasionally, its always worth checking for Water in fuel tank or a dirty fuel filter. Having just bought the boat, the fuel tank is always a good place to start. I removed tank and cleaned lots of gunge and water. then fitted an aluminium fuel filter with a drain tap. any water and be drained off easily.
 
Engine runs but cuts out when put under load - A few quick fix culprits
Potential #1 - If the engine has been fine before but now won’t run when under load, the Coil is a good first stop. It’s a common problem apparently so mounted the coil away from engine to stop it overheating and replaced the coil. I tested the system for ballast just in case the wrong coil was fitted in the first place and then used a performance coil (basically a heavy duty version of the cheap ones)

Potential #2 - The engine may be being starved of fuel which points to a fuel pump malfunction or a blocked main Jet. Again, if the engine has been running fine and this is a sudden problem, it’s worth checking these areas are ok. Try pulling the choke out. If the engine runs under load with the choke out but not when put back in, your issue is carburetion rather than Coil.

Installed a blower - The boat safety scheme apparently does not require a blower for a petrol engine bay, but for safety It’s a pretty important installation,

Refurbished Carb - When a carb is refurbished, the components are replaced as per the manufacturer’s guidelines. This means if your carb has a non standard set up, you’re in for problems when it comes back. Mine came back with a smaller main jet and no small washers on the compensator spring. Both not the fault of the refurbished.
My carb had been set up for my engine. My Ford Crossflow 1600cc Watermota Sea Tiger required a .5 main jet rather than the standard .4.
A big surprise was the value of the small washers that are sometimes found on the compensator spring which mine now has 6 placed under the spring. This controls the fuel when accelerating and the washers make the spring stronger.
The symptom when receiving my carb back was it just did not want to play when I put the boat into drive. It coughed and spluttered and misfired. Having spent a long time getting great help from both Sheridan Marine and the carburettor exchange in Bedford, we eventually solved the problem with the jet and the washers. Saying that, I also ended up changing Ht leads, Plugs, points etc and bought some great diagnostic kit for future tuning!
You can see videos of the engine with the problem on the Video page