Re: Oil Pump Gasket
#31 is likely an o-ring. This is the back of the oil pump from my F22a1. I was puzzled, and even posted a thread about the lack of gaskets Honda uses on oil components, especially where the surfaces mate. The entire perimeter of this oil pump does not have a gasket! You just use Hondabond (RTV). So, when you remove the oil filter bracket to replace the o-ring, I'd recommend cleaning the surfaces where they mate (acetone worked great for me) and applying a bead of Hondabond. Unfortunately, I already had the engine pulled when I did all of this, so I can't be much help in the "how hard will it be?" department. Good luck!