After hours of head scratching and lots of rope pulling on my 025 I finally found a simple explanation for why it suddenly stopped starting. I’ve replaced the fuel lines, new filters, new plug etc. I even cleaned it all out, cleaned the magneto, and checked gap. It ended up being a loose connection at the spark plug wire connector. They use a spring on a barb and it had come loose on the boot. You basically push the wire thru the boot and re spear the barb. I also took the extra step of soldering the wire to the spring. Hope this helps somebody else.