Switched to the Microsoft Natural Ergonomic Keyboard 4000 you linked and have some of the same problems. I don't have any issues with the membrane, but my work keyboard is completely missing the "L" ...

So, My Microsoft Natural Ergonomic Keyboard 4000 is worn down into "Das Keyboard" look almost. I've used many keyboards in the past of this type. A few Logitech, but mostly Microsofts Natural ones, ...

Before I recently discovered that the typing-related wrist pain I was experiencing was caused almost solely by the wrong chair/table height ratio (most tables are too high to be used for typing, even ...