Start with the large oil tank in your battery compartment. I would remove tank from boat and then remove cap from oil tank. Pour oil from tank into a pan and clean inside of oil tank. Then clean bottom pick-up screen and reinstall tank in boat. Fill oil tank to near full, tighten oil tank cap, remove engine cowling, and crank engine on water hose. The large oil tank should flow oil to small oil tank under cowling to completely full. If not, turn off engine and restart again. Small tank should fill and alarm should clear. I have actually done this before with the exact boat and motor you have. The small oil tank under cowling should always be full of oil or there is an issue. In my case, the oil flow was restricted from large oil tank to small oil tank. Cleaning tank and screen fixed the problem.

Try Boats.net or EBay

Went through this on my old boat. Mine was the float inside the oil reservoir located on the engine. The float would intermittently get stuck. Check that, your thermostat and make sure you bleed that same small oil reservoir on the motor. If there's too much air in it, will throw alarm. This is all assuming your motor is pissin water properly. If it's not, check the strainer screen and replace your impeller.

4 alarm beeps is low oil in the engine mounted reservoir, it won't be the thermostat or water strainer I think.