With no compression, I'd blow some air through the spark plug and ID where it is coming from. Don't need much air pressure. It could be the valves are not seating correctly or worse.
If you had a dial indicator, place on each valve and measure stroke. Compare two exhaust and two intakes to see if there is a difference.
Good luck and report back what you find.
2012 JD855D OPS Black Poly Roof, Deluxe Cargo Box, Front and Rear Protection, Power Lift, Front Hood Rack, Rear Screen (homemade), 800 Watt Inverter, 2500lb Winch installed in cargo bed, Front and Rear LED auxiliary lighting (4" square 27 watt), Front and Rear CV Guards, Koplin Side Mirrors