Some help...
Are you concerned that it doesn't run as much as it used to, or that it runs too long?
Manual says the carb cooling fan is an inline 8A fuse. Also indicates relay is in the engine bay on the left side. The motor only runs in the absence of oil pressure, so the oil pressure light switch is part of the circuit (grounds the relay through the fan switch and oil pressure switch), and could be an additional problem.
Hope that's helpful!