I had a similar problem and eventually gave up, something I rarely do. The rubbish aluminium conrod broke just above the bigend. As there was no obvious other damage, the piston moved smoothly and the compression was good, I decided to buy a new piston/conrod for £15.
Luckily before I did I realised the only way of getting the piston out was to remove the counterwight and after removing the gearbox etc push the crankshaft through the other side out of the way. I finally got the counterwight off using a lot of force pushing wedges beneath it but there was no way I could move the crankshaft to access the piston.
Annoying as bit by bit I had practically rebuilt this rubbish machine:-
Blades cracked where they looped over the gear cam.
Cam on gear worn - blades jumping it.
Guard blade broken ( twice ) at root.
Carb rebuilt.
Luckily before I did I realised the only way of getting the piston out was to remove the counterwight and after removing the gearbox etc push the crankshaft through the other side out of the way. I finally got the counterwight off using a lot of force pushing wedges beneath it but there was no way I could move the crankshaft to access the piston.
Annoying as bit by bit I had practically rebuilt this rubbish machine:-
Blades cracked where they looped over the gear cam.
Cam on gear worn - blades jumping it.
Guard blade broken ( twice ) at root.
Carb rebuilt.
