2010 craftsman 21hp wont crank more than 1 rev.

My 2010 craftsman with a 21 hp briggs will only crank 1 revolution then stop, I can manually turn it past that point then it will crank 1 more rev. starting system checks out, I adjusted the valves - no improvement. I have been told it could be an internal compression release on the cam - does this sound accurate and or common? if so is it worth repairing?

Thanks