Think you've solved it! I retrieved the saw from the garage earlier while checking up on my brews.Friend of mine helped me fell a small tree in garen this year , his was a petrol version , throughout the day he said the blade was getting blunter and blunter and that it normally needed sharpening after a days use...
So i suppose it may be new but is it unused ? Also is it possible to put the chain on the wrong way round!!?
I took a picture of the chain on the bar then set about Google..
It appears that the last time I used it I had the chain and bar off to clean it ...and put the chain on the wrong way! The easiest way I found to realise this was to make sure the depth guide spike,shaped like a sharks fin,is "swimming" towards the blade tip...I later found an exact description with sharks on the diagrams!
So in the morning I will give it another go.