Hello, I have an 01 Tiburon that I've been driving for around two years now. The car currently has close to 160k miles and I could tell it went through some abuse in the past. Since I've had it, third gear always had a small grinding problem, but since it never was too much of an issue so we ignored it. Until recently, the car had been working just fine. However, as of a few days ago, when I downshifted on the highway, the car shifted into fourth, then I noticed the RPMs were quickly approaching the red and I pulled it back into neutral quickly. Shortly after that, I realized that fourth gear was completely missing and later I found out that third gear would also not engage. The shifter goes into the position for third and fourth easily, but the gears don't engage. I looked under the hood and found the piece that actually does the shifts on top of the transmission and manually tried the positions for third and fourth to no avail. Also, first gear now refuses to even let me put the shifter in that position. What could be causing this issue?