Slow turn over

[Stew]

I had a similar issue. I took the starter out and cleaned the brushes and armature. The starter completely came back to life. In my case, the inside of the starter was filthy. Remember the starter is below the oil fill cap. Over time, oil blow-by mist can accumulate on the starter and cause problems. Good luck

[Jack Shaft]

Next time it happens try hand cranking it..it will tell you if the problem is mechanical or electrical