Can’t wait to see the new videos! I am a transmission repair guy/mechanic. Looking forward to learning something from you might be able to show you a few tricks welcome back!
Work on you, first... When the home fires are well-tended, then spread transmission love out to the world. FYI, I put a Sonnax 1-2 accumulator piston and new housing in my 4L60E transmission during some other maintenance (solenoid and wiring harness replacements). The one-two shift is a touch firmer now. The original springs were left as-is. Granted, the old piston/housing/pin were very worn. But, I'd like to get a feel for that particular hydraulic circuit and how to decrease the one-two shift hit.