1. There aren't any diagrams available
2. The engine is of Chinese origin
3. The engine is not designed to be repaired
4. The engine costs £9.00 to make & Mountfield pay £12.00 for them
5. Whatever has gone wrong it is terminal as it's not designed to be repaired there are few if any spares available
6. If you can fix this problem, then sure as eggs is eggs you will have another one next week.
7. Bin it and buy something with a reputable, serviceable, reliable and repairable engine fitted such as Briggs & Stratton or Honda.
pleasant
May 2010