Cheers Simon,
Don't know anything about the condition of plugs, etc; as I never look at them I just check the oil level occasionally, but obviously not enough. Last time I looked the oil level and condition appeared normal about 30 hours ago. Regarding the engine running I have had no problem at all, or reason to suspect anything wrong. On the rare occasions when I do give it a short blast it hits the 5,600 rpm figure, although I usually run it at around 4,200rpm giving me a very economical 20 knot cruise speed.
The dealer has already checked the cylinder compression and found that it