Two interesting possibilities. I would probably discount the first suggestion regarding the vertical CG placement, though plausible, the design of the Arrow precludes having equipment far enough from the center of lift to have an impact (the fuse top mounted pipe puts all the equipment at or slightly above the C/L with no real option for relocation). The nose heavy condition is logical, but Yak13 added 3 oz of nose weight and observed a slight improvement in the aileron sensitivity. If the Arrow was nose heavy enough to cause unwanted roll issues I would expect it would require significant up elevator trim to maintain level flight and have very 'mushy' elevator response.
Of course it is very hard to make a diagnosis from 3,000 miles away (or more)! I think we need more information, here.
After looking more closely at the photo of your Arrow, I wonder if that is an original Arrow or a Quality Line (Hobby Barn) Arrow 800. The wings appear to have more span than the original Arrow. The original Arrow had a span of 63" and a length of 55". What are the dimensions of your Arrow? Also, what is the construction (wood or glass and foam)?