I have been a little slow here, but I had problems getting the dirko HT delivered and I have only just re-built the chain saw with the new ring installed. I used a very small amount of Dirko on the seal.
I have not tried to start it yet, because I would really like some advice to help prevent this problem from recurring. I really appreciate the help that I am receiving on this forum. Thank You to all!!!!
First of all I must point out that I tried doing a compression test yesterday and unfortunately I was very disappointed in the result. It measured a 100psi which I believe is not great?

Could this be because it needs to bed in before I do this test or could it be another problem?
Clutching at straws but it might be the decompression valve? Originally when I discovered about the compression problem(before the new ring fix) I did check the valve by putting soapy water on it. Unfortunately i did not dry this off and the button had seized (rusting while I was trying to fix the saw)
I soaked it in some oil and had to lightly tap to free it. I think that it is working ok, but my inexperiance might prove me wrong!!!
Moving on, why did I get this problem in the first place? I have been told that it was probably due to old fuel (which possible might be the case)?
Are there other reasons that this might occur....e.g. carb settings or to much oil in the mix? I dont want to try and start it until I know a little bit more.
I did make a stupid mistake early last year, in that I placed chain oil in the fuel tank. I immediately saw my mistake and I emptied the tank and washed it out with more fuel. But is it possible that this may have caused the problem later?
I checked the fuel filter and have posted a picture of it. To me it looks ok, but again should I replace it.

;DYour probably having a good laugh at all the mistakes that I appear to be making..... To be honest I only use the saw 2/3 times a year....perhaps i simply need more practise

Sorry for the long message and thank you so much for your valuable help.