2004 Hyundai Accent Transmission (Overdrive?) Issue
 

I have a 2004 Hyundai Accent GL. Up until last summer, it was working perfectly fine. I drove about 50 miles up a mountain to visit family and unknowingly left the overdrive on (as I always have since I bought it 4 years ago). I'm assuming the strain of the climb + the overdrive did something to the transmission. I took it to Mobil 1 and they told me the problem was called 4th gear failure. Basically the overdrive went out I guess and the car is unable to shift past third gear into 4th. I asked a family friend who used to be a mechanic about it and he said this is a common problem for the overdrive in Hyundai transmissions.

Mobil 1's estimate was about the same value as the car's worth and I can't afford that ($2000+). The family friend I asked gave me multiple alternative options, the main ones being to remove the overdrive and replace it, buy a brand new transmission, or buy a used transmission.

I guess I'm looking for other opinions on this issue, or other options that I have. The car is actually a really great car otherwise, and since last summer I've still used it as my daily driver and other than the fact that I can't go on the highway or go past 50 mph, it hasn't exhibited any other problems. I've switched off the overdrive and as long as it remains off, the car operates without issue. I feel like I need to figure out the best way the fix the issue before anymore gears fail or the car quits working altogether.

Any responses are much appreciated