ne hole doing a service on our Beta 43 engine,changing the oil in the engine and gearbox as well as replacing the air, fuel and oil filters. We bought the oil and filters at Wrenbury as the chandlery sells Beta filters. Soon nearly finished but the priming of the fuel filter wasn't working. Question...what's that little nut for on the side by the fuel filter......loosened it and continued to prime the fuel filter...air came out and problem solved. First time we've had an air lock in the fuel system. Nearly ready to go cruising!!