First, what is strange about the finger is that there is no numbness. Rather, when the hand is laid flat on the table, I can not raise the finger. It is exactly what you hear reported when someone has a spinal injury - i.e. that no matter how hard you try, there is no movement - but in a curled position, I can raise it- though my control is not absolute.---The moral -aging is a bitch.
The problem with practicing jazz lines, as I mentioned in the earlier statements, is that, in aural learning, our thought processes are , to a significant degree, a reflection of the sources to which we listen and the relative ratios of those listening experiences. When one spends extensive time practicing one's lines- you become your greatest influence. The result is that one becomes less flexible, more locked in to certain tendencies.
The problem is basically one of "how to practice improvisation and avoid locking in phrases".
Our lines emerge in part as a function of the surrounding accompaniment. As an obvious example, a player with a predominantly Trane influence playing rhythm changes, will have trouble playing his lines within a dixieland based rhythm section, even though they are familiar with the changes. It is a round peg in a square hole experience. This, by the way, is why my solos are so different between Knight/1000 Is and After You've Gone. The rhythm section is creating radically different feelings, and I do not fight the section-- I let emerge what the section is dictating.
This context phenomenon can be used to great effect in the practicing of improvisation- or more specifically, thinking through your horn.
What I do is practice thinking via emerging lines that have no applicable context in jazz. What I refer to as neutral phrases.
I use Bach-like phrases (Get a copy of the Well Tempered Clavier-initially listen to it, but do not read it before you start practicing to establish a sense of sound). I start with fairly conventional phrases to establish my sense of tonal center (key). Throughout the session, my thoughts (emerging from the horn) become more complex harmonically- but still neutral. I set up parameters such as starting successive phrases on a different note (eventually starting phrases with all 12 tones) and resolve to the tonic. or end a phrase on a different note- eventually encompassing all 12 keys- I will keep ending in a certain note until it sounds logical to me. I will create ascending phrases, descending phrases rotational phrases, long phrases, short. I will create phrases on the lower, middle and upper ranges of the horn. Follow a slow phrase with a fast phrase. .If I feel that I am weak in a certain range of the horn - I will create phrases in that range. I am constantly examining my playing for "tendencies" then create exercises to strengthen non tendencies.
But always I am setting the parameter first-then letting the sound emerge - not allowing pre-thought or pre-visualization. One of my mantras is- when you pre-think, you are dead. If what emerges sounds right- then it is right.(What sounds right to us is a function of our listening and not whether it corresponds to a rule of theory or structure).
In this way, I have taught myself how to think through my output. How to accept my output as valid. This is the technique that I developed 40 years ago when I was trying to figure out a way of playing freely in concert A and E for rock-I still use it today, religiously. It is exhausting - particularly in conjunction with the exercises that I sent you and is the reason why my practice sessions last as long as they do. But in addition to training thought, it also builds mental and physical endurance.
Obviously, this, in itself is not enough - next topic: Critical listening.