I've had this FR651V that is a "hard/slow crank" to start for a few months. I asked early this spring about engine swaps but got busy mowing with my Scag and this has just sat. I'm quite convinced I've a "compression relief" issue, valve rocker lash seems quite close (used .002 and .004 to check cold). I have the service manual but it's somewhat vague as to explanation of possible single component replacements internally. I've swapped 3 starters and all have the same slow to crank. battery...
FR651V Camshaft replacement
FR651V Camshaft replacement