Thanks Karla, ill do that.
Just for an update, i bought a new bar a new chain a new needle bearing and a new sprocket. One of those four seems to have fixed it. Needle bearing and sprocket were very easy to replace. If i had to guess it was the sprocket that was causing the problem, it was very worn. thank you Karla your comment about the sprocket meeting up with the chain correctly, made me change out the worn sprocket. Fred
Thank you, i will check these this weekend!