The trans computer resets itself when you turn off the vehicle. When you turn on the vehicle the trans computer goes through a set of diagnostics, and when you drive the vehicle the trans computer continues with diagnostics that run all the time. If the trans fails any of those diagnostics it is immediately put into limp mode by the computer.
Limp mode is designed to save the trans and parts inside of it from further damage. A number of people in the past have discovered tricks to keeping their trans from going into limp mode - like your O/D button push, and like stopping in traffic and turning the key off then starting back up again.
If your trans is going into limp mode due to a sensor malfunction, doing the above tricks is going to ruin it.
If the problem is a case like yours, and a fluid flush doesen't cure it, then the trans is going to have to be taken apart anyway to be fixed, and if you can get some further life from it from locking out O/D then you might as well go for it.
Adjusting the low/reverse band is easy, you'll have to remove the parking sprag pushrod (e-clip) to gain access, then loosen the locknut with a 13mm open or box end or socket. The adjusting nut is a 6mm hex (I think that's what I used at least), torque it down carefully to the FSM spec then back it off the number of turns specified in the FSM. I painted two stripes 180 degrees apart on my 1/4" to 3/8" adapter to see when I'd gone 1/2 and one full turn.
Hold the adjusting hex when you tighten the locknut so it doesn't move. Don't forget to put the parking sprag pushrod and e-clip back in! Adjusting the kickdown band is also pretty easy, it's on top of the case under the throttle cable. It uses an 18mm locknut and an 8mm hex adjuster. Use an 18mm box end to loosen and tighten the locknut.
The 4 speed Ultradrive A604/41TE does not use bands. It uses clutches. That is why you were given Clutch Volume Index readouts. The 3 speed automatic that is fully mechanical is the one that uses bands. Your reading the procedure for servicing the wrong transmission.
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