I foolishly tipped my lawnchief 420 on its side to carry out a minor repair to the guide plate. I think I may have spilled the oil into the carb. Now the mower struggles to start. It will start if I persist. I have removed the spark plug cleaned it using a dry lube solvent. Cleaned the plug and set gap with feeler.
I am an engineer to trade so even if someone could point me to a web site with diags I would very much appreciate it.

Air filter has a paper element and is probably soaked. Try it without and see if that works.

Don

Thank you for correcting my mistake, the forum is used as a tool by many, posting what DID work would be a great help.

Don

Wow thanks don that was even MORE helpful this time.
Mate if I had wanted a guess I would have asked for one.
The filter is made of sponge and I had already changed it.
I have not posted what DID work, because I have not GOT the answer yet!

Pushed a button, sorry if I have offended you mike. Let me try again without sarcasm.

When a mower is tipped up the oil from the crankcase can find its way into the carburetor throat via the vent tube. No real damage is done it usually just soaks the air filter and chokes the engine out causing hard starts and poor running. If you have checked for this then the problem may not be related to tipping it up.

Don

I appreciate that Don, thanks. It did push the wrong button mate, I'm sorry too.
Anyhoo, I did get the answer eventually from a very nice helpful man at my local B&Q DIY store. It turns out I have a 4 stroke petrol mower but I have been operating it as a 2 stroke on the advise of the guy at the shop that I bought it from originally. So I had been mixing the petrol with the oil 50:1 . So the mower had worked fine as the oil in the petrol was lubricating the engine and keeping it cool. So I had never burned any of the actual engine oil in 2 years. So when I spilled the oil, the engine was running dry and obviously hot... Long story short... topped it up with 10/40 oil and Bobs your auntie.
Ps it is also so much quieter... funny that.