I have acquired two Claviettas recently, one that was in playing condition except for a broken black key and the other a “donor”. The tricky thing about replacing a key is working with the spring. It’s very hard to hold the spring down and engage the tiny nut. I held the spring down with a screw driver tip, but one slip and the spring is launched off into the stratosphere. The first Clavietta (older one with red trim) has very good rubber washers, while the washers on the donor were a shade of brown in color (as in Oskar’s photo) and hard and brittle, mostly in pieces. Now that the first is repaired, it plays and sounds good. But there are two issues: (1) The key action is uneven, some less springy than others, and I’m wondering if I should tighten the spring nuts on some of the keys. (2) There is a lot of leakage, too much. There is some (specky) corrosion on the plate on which the rubber washers sit and around the rim of the metal reed cover where it meets the gasket. I’m thinking I should use fine grade sandpaper to clean off the corrosion. If anyone has any ideas about other possible sources of leakage, I’m interested.