George wrote about Maggio helping Mendez.
Mendez was working in a factory in Michigan when he was "discovered" and hired to play at the Fox Theater in the 30's where he played with a Detroit guy named Emil Gowatch. Emil told some stories that I got second hand about those guys having to play three shows a day and that they would "lose their chops" after doing that much tough work. I don't know if this is related to the story of Mendez getting his chops seriously smashed in when someone came bursting into the pit at the theater. Mendez couldn't play for a few years. This is where I'm not sure about the timing of Mendez and Gowatch traveling around the country to take lessons and seek out advice about "getting their chops together" They spent time with guys like Herbert Clarke, Ernest Peachin, Geo Gustat and others as well. Emil said that part of what they discovered was that the top lip must not be crushed, that the bottom lip can take an awful lot more pressure than the top. Therefore, one should anchor the mouthpiece on the bottom lip. I spent only one hour or so with Emil when he was 86. He used to do push ups with his lower jaw. He would lean against a pole or something and do jaw push ups. He asked me if I wanted to hear a high C. So I said sure. He went for one and missed. He got a D instead. 86 years old.
Mendez tells the story that it was his father that helped him the most in recovering from his lip injury. But it took several years and several surgeries before he was able to play again but he made the term "comeback player" an understatement.
As for the great teachers, the late John Coffey, bass trombone player, (originally a violist) used to teach all comers in his store in Boston. Bill Chase, Don Ellis, and a host of others sought him out. He was a straight ahead guy who wouldn't take any shit from anybody including Toscanini. He threw his trombone at Toscanini during a rehearsal. He got blackballed for it but was such a great player that another orchestra hired him soon after. Anyone else with John Coffey stories or students is welcome to add to my mini list.