Start by undoing the rods which may be quite awkward depending upon where it has stopped.
Push the rods up into the bore
If the flywheel is not off, take it off as you will need to remove the crank shaft.
Was not expecting you to get this far this quick so just in case you have not been doing it,,,,, TAKE LOTS OF PHOTOS
Engine with part in, then the part by itself then the engine with part removed.
If the engine is rebuildable they will come in handy,
If it is only the rods then rebuild.
If the crank has seized on the top or bottom cases then it is good night Irine.
The bottom case is replaceable for a reasonable price , but the top is a full short block which is not much less than a completer replacement engine from one of the surplus engine suppliers.
There iis no bush where the crank goes through the cases and the clearance is around 0.001" to 0.002".
I have seen some fitted with bushes but that requires a friend with a good workshop and a taste for a nice burbon :licking: otherwise the cost is way too much.
Go to Kohler.com and download your engine manual and your engine parts book.
Log on as guest when the log on screen appears.
The trick is to get the rods off and out of the way, then take the plugs out , bolt the cases together and try rocking the flywheel and the PTO shaft
If it moves left right then the engine is toast.
Up down you should have around .020" to .050" but left right is the problem.
If the crank has a build up of alloy on it where it goes through the bottom then that needs to be removed first .
When I started out I got hold of some large diameter key rings which I put a company tag on.
The mowers were always left with the keys hanging over the dip stick & i encouraged customers to do the same so it reminds them to always check the oil.
There is SFA oil in there and by the time it drops to the end of the dipstick you are doing serious engine damage.