I recently purchased a mint, never played, Aria Pro II ZZB bass - 1985 model. I adjusted the truss rod 1/8th turn to straighten the neck and changed the strings to Rotosound Swing bass 105's. Both the original strings and the Rotos are very hard to play fingerstyle. Fretting is not a problem and the neck feels nice, the right hand is what i'm having trouble with. Any ideas? Btw I've used Rotos for years and never had any right hand fatigue. Could it be saddle height?