I've found that when slurring between certain notes the sound is changing to a horrible squeaky noise. If I do the same sound but tonguing this doesn't happen. An example of where it often happens is switching between B and high D. It doesn't happen all the time, maybe only 1 in 4 times. I've noticed that when it does happen that the octave key pops up for a split second. I think I've narrowed down what exactly is causing this but I can't think of how to stop it. If I'm playing high D, my fingers are down on the octave key and 6 other keys, the octave mechanism will be down (even though the octave key is depressed). To switch to B I need to release 5 keys and the octave key simultaneously. What I seem to be doing some of the time is releasing the third key down a fraction of a second before releasing the octave key. This means that the octave mech is going up and back down causing the squeak. Now, what I'm trying to do is release all the keys at the same time. This inevitably means that occasionally one of the keys will be released quicker and caused this problem. I can't see how I can stop this from happening. To release the octave key a little bit before the other keys seems to difficult to be realistic. Has anyone else experienced this? How did you overcome it?