Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Surely 0.4v can't be the difference between starting and non-starting?
I can't see how the battery would cause a malfunction in one pot and not the others. An ignition fault is more likely to cause 2 pots to fail unless it's the HT cap - try swapping 2 and 3. I'm thinking you could have low compression on pot 2. Worth checking.