Ok, I'm an old and outdated contrarian, but.... What the hell is the point of these things? My 1882 Knabe has a key cover that works just fine. It's not going to offend anyone's pinkies. You want it closed? You close it. You want it open? You open it and it stays open.
Properly counterweighted keycovers have worked for way more than a century. And now, suddenly, they are a problem? Why?
It's an invented problem that didn't need fixing brought on by a lousy choice of materials.
My old Knabe keycover is made of a relatively thin panel of (probably) poplar faced with a rather beautiful mahogany veneer. It is reasonably lightweight and stable. This one is not counterweighted, but many were, with lead weights. (Check out Steinways built during the last century or so.)
No tricky mechanisms involved. Just appropriate materials and good engineering.
Suddenly we have to improve on this. Why? Well, because the materials have changed. Key covers are no longer made of poplar-core laminates. They are now made of MDF (medium density fiberboard) which is considerably heavier than that old stuff. But it's cheaper and it looks better under those high-polish polyester finishes that we seem to be in love with just now.
But this new stuff is a lot heavier than that old stuff. And that can be a problem. (Another story that involves a court trial but which I'll not go into now.)
So, rather than figure out how to build a less massive keycover (LDF -- low-density fiberboard is available) the industry has decided to develop these "slow-fall" mechanisms. Complex, prone to failure, and difficult (if not impossible) to replace, but a great marketing tool nonetheless....
I hate these things.
-- Delwin D Fandrich
Fandrich Piano Company
Piano Design and Manufacturing Consulting Services -- Worldwide
6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
Phone 360.515.0119 -- Mobile 360.388.6525