Hi Patrick,
Glad you’re liking Art of Reggae. It’s a work in progress and will get better and better!
Wow, now there’s a problem I’m not sure I can help with. You’re going to have to pioneer new fingerings for the scales and even the bubble chords with your left hand. I would think playing chords with the missing finger would be easier than trying to play scales in unison with your right hand. I do remember some many years ago injuring one finger on my right hand and I had to tape it to an adjacent finger(maybe it was a middle finger to the ring finger) and had to play a jazz gig. I found the challenge to inspiring actually as it forced me to play differently than I had ever before and at least in the jazz realm that worked. I was glad to get the use of the finger back however(!)
I didn’t mention this in any of the videos but sometimes I bubble (LH) not hitting any chords at all but just kind of punching any notes in that proper bubble range to just get a percussive sound and that can work great.
I don’t know if this is of any help but those are my thoughts at the moment. Let me know what you might come up with in doing the scales.