I have a HARD downshift at 20mph (I am assuming 2nd to 1st gear??)

acceleration is fine. if I "let off" the gas while accelerating such as in traffic (and OF COURSE traffic always seems to average that magic 20 freaking mph) it will many times "slip" into neutral and when you press the gas to go again SLAM into gear. so I have to remember to "tap" it and feel if its slipped or in gear before pressing harder so it does not do that (I can't imagine its good for the gears etc..)

many times in stop and go I will put it in neutral as I approach deceleration to 20mph and then put it back in drive once below 20mph avoiding the hard downshift.

I got a used valve body assembly (its my understanding this is where this problem is located ???) and installed it. refilled with proper k fluid ($15 a freaking quart !!! s*** that hurts $60)

still does it. but its "different" now. not as hard hard to describe but its clearly not "quite" the same almost as if the car I got it from has the same problem but earlier not "as bad" but still doing it.

I was told I can rebuild this unit with some widgets inside (solenoids or something like that ???)

is this correct? does that sound like the problem? and if yes is there instructions for doing this and a list of the parts and what not I need to purchase to get it done? figure I will rebuild the original one and if practical rebuild the replacement as well so I have a "good spare" on hand in case it does it again.

moving cross country and need this vehicle running "right" when I leave as I will loose access to my mechanic friend who helps me with complex repairs (such as this) as I will end up 2000 miles away from here. (PA to NM)