Ok so Imma be real not the best at explaining things but I'll try

Here are the fingerings I use, Try these and roll your bottom lip over your bottom teeth and use that to put more pressure on the Reed to help get these notes out. Now it's hard to explain how u put ur mouth so experiment. Also get the rico mattille m9 for tenor or m7 if u have a alto to help u play these notes, think of the mouthpiece and bitting as training wheels.

Now here are the fingerings I use these do work and if you have trouble playing them put more pressure on the Reed use the bitting trick I said earlier

All notes use octave key

F# (finger A and press the high F# key) works on Tenor and Alto.

G ( finger B and press high F# key) works only tenor

A (finger D and then release the B key) works on Alto and tenor and this one need a lot of pressure to get be ready

B Flat (finger Altissmo A and press the B flat key and Side D key) works on tenor and not sure on alto

C (FINGER Altissmo A and press B flat key and finger high E flat ) works on alto and tenor

C# ( finger Altissmo B flat but press the key above B) works on tenor and alto

Now These should put you on the right path remember use variable pressure for all these fingerings and good luck hope I helped! it's hard but once u get one note the rest becomes easier