My engine locked up while running WOT. After pulling plugs I can see that 1 piston does not move at all. The crank will only turn about an inch in either direction. There are no holes in the block, or fluids leaking that I can see. If this is rebuildable, does anyone have any idea what it might cost? Would I be better off buying another rebuilt powerhead? Thanks in advance if anyone has any info or advice.

pull the bottom plug out of the lower unit see what it looks like if it smells burnt an has pieces out metal drop the lower unit a broken pinion gear will lock up the works too.

Wouldn�t all of the pistons be locked up though? I�m sure it�s in the engine.. I lost power, then it stopped abruptly..

Does the prop spin freely when in neutral?

yes

Having someone rebuild would be big bucks. Only way a rebuild makes sense money wise is to do it yourself. You would be very surprised how simple these carbed two stroke are. If you have a service manual and a little common sense, you can do it. I�ve rebuilt two motors now and both turned out great. Bought my last boat for $600 because the Johnson 140 had been overheated. Cost me $1300 to rebuild it, and now have a nice little boat. If you don�t want to take on a rebuild, then finding another powerhead is the way to go.