Hello everyone:
I just took my Lambda Pros out of storage after 10-years. I immediately noticed a flapping noise coming from the left driver, so I took it apart to investigate.
There's a fine-mesh screen affixed to the rear of the driver that came partially un-bonded, causing the aforementioned flapping noise. While I was in there I noticed that the black foam basket netting and fibre acoustic insulation was de-composing (dry-rotting) from age, so I contacted Yamas/Accutech, the Stax authorized service agent in the US for a replacement parts quote & availability via e-mail.
I received a very professionally detailed reply from them the following day, completely answering my questions along with a parts quote.
They explained that the fine-mesh screen was not available as a replacement part, but only with the driver unit itself. They stated; however, that it could be easily re-bonded with a gel-type adhesive.
I ordered:
* a pair of two basket acoustic insulators
* a pair of two black foam basket nettings
* a pair of two replacement earpads w/mountings
The creaking, or crackling noise that you're referring to may have two possible origins:
* One being the yoke pivot pins, as previously stated.
* Air pressure differentials on the driver diaphragms, rattling them, when re-positioning them on your head. I've been told this is normal on a well-seasoned driver.
If you're familiar with drum heads the same logic applies here, as drummers claim them to sweeten with age.
My Stax have ALWAY made a crackling noise from right out of the box, as well as several, but not all, other pairs that I've ever listened to over the years. Someone once told me that they'd rather hear them crackle/flap when re-positioning them, rather than lose their detail, imaging, openess & transparency.
I used Spirit Gum to re-bond the fine-mesh screen to the driver unit, by rolling the gum onto the driver flange with a Q-tip, allowing it to tack up prior to re-affixing the screen.
After re-assembling the cans, I applied Silicone Plumbers Grease (very THICK) to the pivit pins with a toothpick prior to their insertion.
They're BETTER than new for about $100.00US including tax, shipping, handling and an hour of my time.
The reason that I say BETTER than new, is because the diagphragms are broken in and the yoke pins don't creak like they did when they were new.
I did an A/B comparison with my freshly re-conditioned 23 year-old Lambda Pros and nearly new pair of SR-507s.
6 out of 6 people claimed there to be a negligable difference on the basis of their openess, transparancy, detail and soundstage image per various acoustic music program control variances.
Good Luck with your project . . .