I am nothing more than, at best, an advanced beginner, in the art of fly casting but I suppose anything is possible. There may be some breakdown in the fibres in the rod. I wonder though, have you tried casting a 9wt line on it? There has been so much "improvements" (so say the mfgr's) in lines in the past 3 yrs that you may find the rod handles todays 9wt line like it did "yesterdays" 10 wt. Many head lengths, of WT Fwd lines, have changed, to deal with the "faster" rods of today. If you still have an old line that you felt comfortable with, try grass casting it and then try new line...just a thought. Sounds as if you are in the market for a new rod, so justify it by declaring the old rod an antique, ready to be relagated to the corner of the closet!