My 1984 SD was shifting hard, too early & under about 30mph often wouldn't downshift. At stops I had to bury my foot to the floor & creep forward until the car got some momentum. I had good power if I manually shifted but it still banged in gear. I went through your checklist in "Diesel Performance Tuning & repair" manual...
All I did was clean out the 'banjo" fitting, replaced the rubber intake elbow seals in my turbo, ran it hard (or as hard as I could get by with on an island with a maximum speed limit of 40mph) and my shifting is near perfect & I have more power. I haven't even tweaked the ALDA fitting or any of the other suggestions!
With your checklists I also feel more secure taking the car off the island on long trips. less fear=more enjoyment
Thanks.....James M.