Just goes to show that the old adage that "most carburettor problems are the magneto" is true.
It just occurred to me that I had fairly much the same issue a few months ago; had the Maggie rebuilt mid-90's, was told it'd outlast me...
but not so. Was running fine-ish, but then just died on me one day. I ginned around for a coupla weeks with carb and spark and beer, but gave in and gave it to the helicopter magneto guy and is now U-beaut