not shifting into 3rd untill high rpm


My TTA has a problem going into 3rd gear. Absolutely will not go into 3rd unless rpm's are close to 3000. And that is with adjusting the TV cable extra loose. With the cable set the way they are 1st to 2nd happens at about 1400 and 3rd to 4th about the same. Before adjusting the cable it would not go into 3rd untill almost 4000 rpm - ouch. Is this possibly something simple like a sero or spring. I am very tranny illiterate but am scared to take the car anywhere. Have had more than a few nightmares with repair shops.