Keyboard Glock number two, a more modern instrument than the first instrument (981) with better mechanism and better construction, even including sign writing on the inside of the keyboard lid. I get the feeling that this instrument was made at the height of Boosey success.
First of all, everything needed a very thorough clean. Some minor repairs to the keys were needed, and the case which is dovetailed needed to be separated, cleaned and glued. The lids also needed repairing having split down the length.
The mechanism needed new felts as the old ones were moth eaten, and de-burring (even 100 years ago no one seems to bother removing swarf!). This removal of burr (tiny bits of metal, on the edge of holes or saw cuts) means that the mechanism now slides freely. Attention to detail is high quality, but actually its the little things that make for a nice playing instrument.
So the designer has come up with a better mechanism. The key is now just a lever, the only striking that occurs is between the hammer and the note. The hammer is mounted on thin brass sheet which provides the spring to enable the hammer to rebound off the notes. Double hits are prevented by adjusting the bend in the brass spring.
The whole hammer mechanism is reversed to play the front row of notes, but everything else remains constant. The momentum of the hammer can be adjusted at the end of the brass spring by altering the height of the fulcrum. Where the spring rests on the key it is screwed through a slot, this is where the burr was which created drag.
Finally notice how the fulcrum of the key is further back because less movement is needed at the inside end of the key. This increases mechanical advantage which equates to musicians as “feel”