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I recently got a very nice Eastlake S20 alto that quickly developed the oft reported “sticky” octave vent problem. After much time spent, I have apparently isolated and “solved” the problem. Time will tell but so far, its working the nuts.
I’ve concluded that the problem is down to a sloppy octave linkage particularly the pivot widget. I noticed that due to wear and/or (IMO more likely) poor machining/qc, the upper ball joint at the limit of travel actually created a camlock situation and therefore needed more force than was available in the neck spring in order to start the body octave pad moving. Not being a tech and not wanting to have the entire linkage rebuilt similar to what Stephen Howard shows on his site, I decided to try wrapping the ball ends with Teflon in order to minimize the slop and the irregularities in the “sockets”. It worked!
So how does this jive with the cork octave pad? Well I think how that works (or would work on mine at least) is that it makes the effective thickness of the pad greater and therefore when the linkage is setup, the upper end ball joint of the swivel widget travels less which keeps it from twisting all the way to the “lock” position, so to say.
I think this problem may be a case where originally some marginal parts were used and the resulting accumulated error plus wear wreaked havoc. YMMV...
I’ve concluded that the problem is down to a sloppy octave linkage particularly the pivot widget. I noticed that due to wear and/or (IMO more likely) poor machining/qc, the upper ball joint at the limit of travel actually created a camlock situation and therefore needed more force than was available in the neck spring in order to start the body octave pad moving. Not being a tech and not wanting to have the entire linkage rebuilt similar to what Stephen Howard shows on his site, I decided to try wrapping the ball ends with Teflon in order to minimize the slop and the irregularities in the “sockets”. It worked!
So how does this jive with the cork octave pad? Well I think how that works (or would work on mine at least) is that it makes the effective thickness of the pad greater and therefore when the linkage is setup, the upper end ball joint of the swivel widget travels less which keeps it from twisting all the way to the “lock” position, so to say.
I think this problem may be a case where originally some marginal parts were used and the resulting accumulated error plus wear wreaked havoc. YMMV...