2MTT's (Lucas racing mags) need to be overhauled every couple of years. They usually signal their need by cutting out when they get seriously hot, but starting first bump after a few minutes. Don't ask how I know this, but I run a PVL system now, with the mag as spare.
I think that until relatively recently mags were prone to fail soon (two or three years) after overhaul because the new condensers were crap and not fit for (magneto) purpose. I believe that Dave Lindsley had proper ones made.
However, while it is possible that both the twin mag AND the Pazon powered Sunbeam are going to glory, I'm blaming new NGK plugs for now.
I think that until relatively recently mags were prone to fail soon (two or three years) after overhaul because the new condensers were crap and not fit for (magneto) purpose. I believe that Dave Lindsley had proper ones made.
However, while it is possible that both the twin mag AND the Pazon powered Sunbeam are going to glory, I'm blaming new NGK plugs for now.