You may be one of the very rare examples of a DIYer who gets the horn playing well and reliably, but if not, then it does not make sense to palm the instrument off onto a string of beginners who give up playing, not knowing that the instrument is the problem, and thinking that the player is useless.I find myself in the middle of overhauling a 1983 Alto. (Selmer Bundy II). Frankly it is my first Alto, and the project is going well.
Please note, I am not doing this myself because I am cheap. I am doing this myself because I am going to turn around and donate the instrument to my son's school, and the instrument isn't worth $500.....so it wouldn't make sense to have a professional overhaul it....
It must be in your imagination, because how far the G key opens is totally irrelevant to the pitch of F/E/D/Low C.... Needed to lower the G key some more too. Fixed the problem.
(Or perhaps the G key's pad was badly not sealing and something you did make it seal better???)