Let me step in here and explain what was done to this saw.
It got a complete and I mean complete top to bottom rebuild and I might have ran a tank of gas through it before Nate bought it from me.
It got new crank bearings, thrust washers and crank seals. The oiler was completely gone through with a new diaphragm, quad ring and gaskets. It got a new sprocket and bearing. The top end was ported a bit (intake and exhaust) no base gasket (I think). I think it got a new piston, but it's been a while but if it didn't get a piston I know it got new rings.
Of course the fuel system was gone through.
If Nate only run it a bit it's probably just now breaking in.
I know I probably spent as much in parts as what he's asking for it and it was a good strong running saw. Most 3700's are at that but this one is even better.