To the OP:
I know you said you changed plugs. Question is did you get rid of the as equipped Chineese plugs and go with plugs made in Japan? Next question is are you sure both plug caps are seated firmly on the plugs? Then the. Ext question is what input vtage is your ignition battery? Could be a switch that is bad as well. Also check the insulater from the carb to the engine and make sure it is not cracked or loose. It needs to be tight but not guerlla tight. Sorry about your injury. I got bit a couple of years ago and I feel your pain. I now wear a leather glove when starting a gas engine. Wish you well
glenn