Hi, Mark – the keys in my German Piano 36 (gold trim) are also noisy, but now that I’ve been in there, I don’t really see any mechanism that can be changed. The key operation method consists of the key, a pivot point, a metal link, a pallet valve (what I’d call it on a reed organ), and a felt pad that covers the opening into the reed compartment.
James B. in his 36 repair/dismantle thread is removing some of his keys. You might want to follow his thread.
On a side note, this forum does a great job of getting us to buy up old German Piano 36s. Motivated me.