Caterpillar wrestler,

"riveted...wear to the point where the lever becomes liable to break"

G: I haven't come across that before..only wear enough to make the connection loose and at the other end getting stuck from debris if not been used enough

"...the hook system does not ensure such a quick return of the pad to its sealing position when the button is released"

G:I have experimented with this and if the spring tension is accurate ( meaning a button touch pressure usually of 50-75 gram ) and no defects are present this should not happen. IF however you for some reason wish to use an extremely low button resistance ( with the risk loosing tightness of pads) the riveted system is safer

" The whole lever can move away from the fulcrum when depressed and so take longer to return to its rest position. You have to be playing really fast pieces to detect anything.."

G: I was intrigued by the similar report many years ago but then with a claim that it caused rattle and clicking ( said being inherent with Lachenals) so I set up a test trying to observe the phenomenon. Some escape by the lever did happen, but only at a speed of 2000+ beats per minute - varying a little between different levers. No clicking or escape could be detected at normal/fast playing conditions. ( No-one plays as fast as 2000 beats/min...)

"Perfection would be a frictionless pivot in a split lever that passed both sides of the post".

G: I haven't seen a split lever. Split posts have been tried by several makers (see below) and mechanically this does look better than the asymmetric variant. Ideally I would use that also ( IF using an axis/rivet at all) but adding a ball/bead at each side between the lever and post. The question is if such a mechanically perfected solution would have any significant effect on musical performance...

Chris,

Yes, Rock Chidley used a forked post on instruments with his own label and so did some other old time makers too. Some modern makers/repairers use it also both on new instruments and old ones. I know that some people have had the action exchanged to this type. In theory it does look neat but again - does it really mean any real improvement in practise? And what in such case?