Wow! I didn't think it was possible for a modern ABC to sieze because of the metallurgy. The hotter it gets the more the sleeve expands. I had an OS61fx lose a prop in flight and wailed like a banshee before I could shut it down. When I landed it was impossibe to touch the cylinder head. That engine is still running fine today! Only exception would be if it ingested some debris and jammed. Then a new liner and piston would be in order. Also check the crank shaft for cracks around the intake port.

Good Luck,

Phil