Magneto drive play

Hi guys my name is Karl and at long last got a lister d the start of my collection. Good clean engine had it running 3 times but a pig to start! Have done all the usual things even ground the valves in, the only time it will start is when i've set the timing several times, I can mark it and it wont start again, taken play out of chain but the actual drive from engine has a lot of take up is there a way of reducing this ??