G'day - I have just registered and hope that I am at the correct page?

I have an old lady (not my wife) a 928 which is missing on a couple(?) of cylinders having stood for quite a while. I know 1 plug is faulty and need to inspect the 2 closest to the air-cleaner box, on each bank but cannot access them. There is a groove at the front of the box and at the bottom a bolt. My normal socket (a Gedore) is too fat to reach it - does a normal tube spanner fit and what size? Alternatively I can remove the air inlets and injector fuel lines - which I tried to do. I removed the 2 bolts at the side of the air-inlet and the nut which retains the 3mm diameter fuel-line but the the inlet would not budge. Is it "welded" to the block by age and heat or is there another retaining bolt beneath the dish-shaped part of the injector?
If anybody can respond with help I shall be truly grateful. My E-mail address is careyskanda@gmail.com
Thank you
Keith Carey