Thanks Jolle, I'll give that a go.
What I have found helps is starting the phrase without the octave key, using it only to jump back up to the E5. (I cant get it to jump fast enough without...its a fastish 16th note thing, if it was slightly slower there is no problem with response and its easier to get it to play the high E5 with a bit of attack...so hard for me to slur up that way so far without the octave key)
Its getting better with practice. Taking a tiny bit more mouthpiece into my mouth also seems to help.
What I have found helps is starting the phrase without the octave key, using it only to jump back up to the E5. (I cant get it to jump fast enough without...its a fastish 16th note thing, if it was slightly slower there is no problem with response and its easier to get it to play the high E5 with a bit of attack...so hard for me to slur up that way so far without the octave key)
Its getting better with practice. Taking a tiny bit more mouthpiece into my mouth also seems to help.