Thanks Theo.
I started with the basic checks like I normally do in order to assess the condition of the engine.
1) Gave the unit a thorough clean (pressure wash and air compressor afterwards)
2) Re-gap the coil and replace the spark plug
3) Cleaned the carby and replaced the diaphragm.
Everything else visually looked to be fine however upon trying the engine it wouldn�t start up. It popped lightly and tried to start but didn�t. I then went to check the spark and it was weak and erratic. That is the best way I can think to describe it.

It led me to believe the original coil was never replaced like the previous owner indicated. I think he may have been quoted a price and never followed through with the repair. The original coil was also corroded on the surface so this led me to believe it was never replaced.
I then switched over the coil and voila the engine ran perfectly. I then gave it a good test to try and simulate the previous faults and nothing���.. no faults whatsoever.
Iv included some pictures of the finished product. Apart from a pretty flimsy catcher, it chewed up long grass with ease down the back of my suberb. The 4hp motor now runs really well!
Next question, can something cause failure of the coil and is there a reliable test I can conduct to determine the coils condition as I have not found a failed coil on this type of unit before.
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