What is the big attraction about an 031 ??
There seems to be many of these saws around for an old saw and are still being used by many to cut wood. I don't think parts are that hard to come by if you don't mind spending money on used parts, I don't know about new parts from a dealer, I am sure some parts are available.
A 31 is far from what I would call a user freindly saw, the cover you have to take on and off to get at the carb and air filter is a pain, the choke is in the wrong place to me.
I just let one of these saws go awhile back, before I sold it I cut some wood with it, it is just an average saw for what it is , nothing to scream about. There are better saws for about the same or a little more money. I would buy an older 039 if it was in good shape before a 31, you would be getting about the same thing for an orange handled consumer Sthil saw with a little more kick to it.
Larry