A common problem with the 4K is that, when shut down,, it may stop on the beginning of the compression stroke. If there are contributing factors, such as low battery or a "carboned" cylinder, it may not turn over. This is because there is more resistance than the starter motor can overcome. With power removed from the generator (in other words; don't press the start switch), reach in on the left side, behind the filter assy, where you can feel a blower assembly. Turn this with your hand - it will be tight - remove your hand and try to turn it over again, This usually works. Got this from the Onan repair people here.