I always check spark first by removing the coil lead and mounting a wire clip (eg paperclip) in the coil tower to make a gap of say 10mm to the body. Then at the coil lead and at a plug lead, with a spare plug fitted to the end of the lead.

Failed rotor button is common enough. Aftermarket ones are deadly. If you can't get a genuine one (recommended) I have used a Falcon XF carby one (Bosch GB864) with great success. They look entirely different but fit dimensionally the same.