Small Engines (Lawn Mowers, etc.): Armature magneto, magnetos, tiny spark

Question
I have a Briggs V twin Vanguard 14hp model 294777-0335-01
and lost spark to one cyl. Thought it was the coil so replaced it with part Oregon 33-347 Says it replaces part 492431.
After fitting still not firing but detected very small spark at the lead on the new coil. Much less than the other side which is firing well. Also disconnected the stop wire part 692319 in cas the diodes were faulty..also replaced these. I thought the new coil was faulty but supplier would not take back as was now used. Put the old coil back on and it fired and ran on 2 cyl so put everything back. After running for 5 mins lost spark again. Changed megnetos to other side and swapped plugs etc.
Get full spark occassionally with the old coil and constant tiny spark with the new one, but not enough to fire the plug.
Any ideas?

Answer
Hi Russ
It sounds like to me that you might have a dirty or weak magnet on your flywheel or the gap on the magnetos are too wide. A good gap for that engine is .010-.012. Make sure there is no rust or buildup on your flywheel magnet and on the magnetos. Hope this helps.