89 Johnson 25HP, When I start, many times the starter will turn the engine only one or two rev's then drops out. I have to turn off, then back on again. Sometimes it's only 1/2 a turn, and it drops out. There are no teeth missing on flywheel or starter motor. Battery is good. Could it selinoid, or Starter? I'm using a 600 MCA Marine battery that tests good.