I play a Birdsong Corto bass. It has 31-inch scale length and is strung with DAddario Chrome flat wound strings, 0.050 - 0.105 (set ECB82). With everything in perfect standard tuning, when I manually retune the E string down to D, the other three strings change tuning also. The A and G strings go slightly sharp, the D string goes significantly flat. If I put everything back in tune with the E string dropped to D, when I bring that string back up from D to E, just the opposite happens the A and G go slightly flat and the D string goes significantly sharp. I am wondering if this issue is peculiar to my bass or if most/all basses need to be retuned after lowering the E string. I was thinking about ordering a new bass (32 inch scale length Landing L32T) with a hipshot D-tuner on the E string. However, if use of the D-tuner throws the other strings out-of-tune in a similar manner, it is not an option I would want to pay for. I appreciate your observation.