I was having problems starting my AJS when hot and with general rough running. Assuming it was the Capacitor breaking down I fitted one of those EasyCap capacitor / condensors made by Brightspark Magnetos. [No connection]. What a brilliant bit of kit!
Ok, its a PITA stripping the mag down, but its then easy to disconnect the old condensor [the original one in my case] and solder up the wires as per the instructions provided. Once you have put the mag back together its easy to fit the EasyCap under the points screw. Did that, put it back on the bike and away you go. It's transformed the starting and running - to be recommended.