First thing is to check for spark and if you have spark, then do a compression test (do these before you put any money into it).....I've owned a zero turn Husky for seven years, with the Koehler engine....Great machine!
Or you could simply pull a spark plug, hook up the plug wire to it and ground the plug body, spin the engine over and see if the plug sparks. Very simple way to check for spark. Also, I notice that nobody (unless I missed it) has suggested that a compression test be done.....If it won't fire off...
If you want to make a permanent repair, go to a marine dealer that sells Johnson/Evinrude motors and purchase a flywheel magnet adhesive kit. This is a much better adhesive than JB Weld because outboard motors generally run much faster than the average mower engine and they run for a longer...