I don't know how to say this any other way - it isn't the johnnyrudes that you are having problems with, it is your lack of understanding of how an outboard motor works. If you bought an OMC motor that was abused or simply in need of long overdue maintenance, you will do the same with any other brand and you will have the same problems.
I have a pair of 50 year old Evinrude Big Twins and they are still perfectly serviceable motors. I also own a 36 year old Johnson and a 39 year old Johnson (main engine & kicker), which are on my boat now, and they are very dependable.
As for the JB Weld, its a handy product for a limited range of things. Fixing a crankshaft or a flywheel is not one of them. Do yourself a favor and put the stuff away before you hurt someone.
Sorry if this sounds strong but, you need to hear it as it is - trying to fix the components that you speak of with an epoxy product is both irresponsible and dangerous.