My 1999 Hyundai Tiburon will not shift into 3rd and 4th Gear. Is it The Cable?

What is your question?

I have gears 1, 2, 5, and reverse. When shifting into 3rd and 4th the shifter just flops back and 4th. I followed the 2 cables to the transmission, and if I push down on the piece that they are tied into and move around it falls back into place. then it feels like it is locked into 3rd. Do you think it is the cable? Linkage adjustment? Thank you for your help. It needs to last a little longer to get my son through school.