My bass is a 1964 Fender Precision. I've had it 39 years and though it's not mint it's a beauty. I really like the sound and feel of LaBella medium gauge flatwounds but I'm having a difficult time getting the E string to play in tune up the neck. The barrel bridge is way back and I've shortened the screw but it still plays sharp. I wonder if it's a truss rod adjustment? It seems to me these strings were made for this bass so there must be a fix for this that I don't know about. Please help!