Repair or Transmission Adjustment

Friends The Forum, it is the first time I am writing to you before some manuals (thank you) today I felt like a princinciant, I tell you, the transmission of my avon kicks when making the changes, according to my little to know, it is about the solenoids and/or valve box, but I do not know how to remedy the problem, my plane is a great caravan mod. 1994 Motor 3.3 Who could help me?
Waiting for comment I am ...
carefully
automotive Gamo