JayJay,
It sounds like your rings are worn and need to be replaced. I assume that the engine is a Power Torque one.
1. When you take the starter off do you replace the 'O' ring on it?
2. Is the machine blowing black smoke?
3. When you hold the blade disc do you have much movement from side to side?
Answer these questions first and we will go from there.
Regards,
Bruce