1997 3.4L 4x4 Automatic Transmission Shifting problem

Hi everyone,

I am looking for some advice on whats going on with my car before I invest some money on a new transmission or valve body.

I have a 1997 3.4L 4x4 automatic transmission that I am having problems with. I started it and when I put it in D to accelerate it had very little power although it could put along. The check engine light came on and it was for a transmission solenoid. I can manually make it shift gears by putting it into L and then 2, etc but in D in wont shift. I replaced a solenoid and the check engline light went away however it still has the same problem. The mechanic said when he drained the oil it was clean.

My mechanic reviewed all the wiring and says it looks fine. He then took apart the valve body and said he finds some wear and then it should be replaced.

I live in Central America and to be honest the quality of mechanics is not great. The mechanic has had the car for 3 months now and I have lost confidence but there really isnt anywhere better to take it. I get the feeling that he is not sure that it is the valve body but is shooting in the dark. Because I am in Central America there are not readily parts available here. I would have to buy a whole used transmission of dubious quality here or buy a valve body in the US and ship it.

I was hoping you all could confirm if the valve body is the likely problem. I was thinking that because it can still shift fine manually it is still an electrical problem and not a mechanical problem.

Attached are some pictures/videos of the valve body parts that he says are worn and therefore the problem:
https://streamable.com/ubpfcc

Thank you!