Does the converter lock up? Temp switch will disable 4th when over heated. Reverts to third and should lock the conv to lower temp then engage 4th when cooler.
Nip the bolts up, mine was ever so slightly leaking for years and I just ignored it.
6 months ago I tightened them up and was quiet surprised how loose the bolts were. Problem solved.
I was swearing when I did mine, trying to install it one handed while prying the exhaust back for cleanence on the ground was no fun but still a great learning experience.
If box was removed from car it’s a 5 min job.
Immortality is right. It’s achived by shims.
Transgo do great vids on utube on this subject diy.
I’ve did my own transgo 2-3 kit with vette servo install, includes shimming of band pin. No more slipping
Do Kenworth, Mack and Western star e.g. Get subsidies because they’re still assembled here and many components locally.
Trucks and machinery are still made here in Australia not everything has left our shores.