So I set about the K and N this morning - My brother was visiting so he got roped  into helping and was supporting the tank (full of fuel) as I got the filter in and tightened down the cover he turns and says "My hand is wet and smells like petrol - look its pouring out the side"
so quickly removed the tank and placed on its side to find this

Looks a little odd but I luckily had Gregs tank sat in my shed 


after the drama of a tank swap returned to fitting the last piece from Noggy


and then had the chance to clean one of the downpipes

used astonish and it works well just need to do the other 3 now