The cause of other trouble in response or intonation of your instrument may be traced to the octave mechanism. If it is not in perfect adjustment or if the small octave sockets are clogged with dirt, you are bound to have trouble. You can clean the octave sockets with a feather or pipe cleaner. See location of these holes in Pig. 30. It is important these holes are kept clean. After running a swab through your instrument, check both octave holes to see that you haven't dragged a lot of dirt into these holes.
Under no circumstances attempt to adjust the height to which keys can rise above the tone hole socket rim. The manufacturer made these adjustments before the instrument left the factory and they should not be changed. Some players want greater sharpness and resonance from their instrument and accordingly have the lift of keys increased. Or they may want a flatter and softer tone, and have the height lowered. It takes an expert to do this job, and even the experts are liable to do damage to the intonation and response. When you replace bumper felts for the bell keys, be sure they are of the proper length. If they are too short, the keys will be allowed to lift too high and the tones affected will tend to be sharp. If the bumpers are too long, the lift of keys will be reduced and the tones affected will tend to be stuffy and flat.
Somewhat the same effect as lowering the keys is encountered when the "biscuit" pad droops and bulges into the tone hole socket. These pads have no center rivet and when the felt and skin become wet, they lose their tautness and tend to "belly out." The result is that the pad extends below the level of the pad cup and has the effect of lowering the pad. This tends to flatten the pitch and muffle the tone quality. When your biscuit pads become droopy, replace them with new pads
Don't "monkey" with the key mechanism. It's an intensely interesting piece of machinery but it was built to produce music and not to entertain your mechanical mind.