ignition problems, rain related or just wear and tear?

[darrsi]

http://www.ebay.co.uk/itm/4x-NGK-Resisto...xyHIlTWrRI

These were the knid i bought, seem the same apart from the angle, so hopefully theyll be in there like swinwear.

I also bought some amalgamating (sp) tape thats supposed to form a watertight seal on rubber when applied. I think its intended for sattellite dishes etc.  Seems to me that the screw in method is asking for a fail....has no one manufactured sealed units?

They're just angled versions of the ones i use, no different other than that.
No need to use amalgamating tape, the caps will have a rubber seal on them anyway, and the screw in method has always been the same and works just fine.
Amalgamating tape is made of stretchy rubber/silicone, which once stretched sticks to itself. I use it for minor cable repairs at work when the outer plastic cable gets a small split but the inner cable is fine. It's handy stuff to have about anyway, but not necessary on your plug caps.
Sealed units would just mean more expense, so to change a simple cap would mean another set of coils. No need when this system works okay.