I mean that you can go directly to each of the spherins (in the conservatory, at the top of the jack tower, and down the peghead elevator) to make sure you have set everything correctly without replaying each puzzle completely. If you've been going back to saved games, you may have gone back to a place where something was done incorrectly.
This is just a thought, but I have been assuming that you have completed the puzzles that revealed the hidden spherins. You have, haven't you? I know of one person who set the potentiometer planet panels the same as the ones in the cabins instead of using the spherin settings.
Again, before you strum, check again to make sure Arin's vault (up the ladder) and the main vault (by the strummer elevator) is unlocked according to the button code.
Young at heart. Slightly older in other places.