The old Torqueflyte 3-speed box did have user adjustable brake bands. The 4-speed ZF does not.
As said, the Ashcroft site http://www.ashcroft-transmissions.co.uk shows many common problems.
Whilst they also are undecided as to whether its a good idea, the first action with many autobox problems - after checking the fluid level is correct - is to change the fluid and filter. Blocked/partially blocked filter causes many problems. And if its playing up anyway you have little to lose.