OK, here is one "get out of jail free" card.
I think mainly you and I say "excuse me for butting in" for the benefit of the person posting the question, don't we? (Don't frighten the customers!).
I have absolutely no problem with any advice coming from you at any stage, my friend. I don't consider it to be butting in. I can't see that I would ever consider you were stepping on my toes. More a case of "Phew, fixed!".
Quite often one of us has a piece of information not known by the other and we can jointly save a lot of time getting to the root of the problem as we work togther.