Best thing to do when you acknowledge a weakness in one area or another is to attack it full on. Learn a simple song in one key. Now ditch the sheet music and play it by ear in that key. Now play it in every key, by ear. Sure, struggle a bit with some keys at first but the more you do it, the easier it gets.

But sheet music is really a shorthand system. It isn’t REALLY what you should play. If you saw an actual computer transcription of a pro player’s rendition of a tune, it would be unreadable as the computer tries to annotate the subtle timing things the player did!

So ditch it as fast as you can! Make yourself a little chord chart if you need that, but get away from a written lead line. What you come up with will be far better!