I have a 2001 Prizm with 5-speed manual transmission. I’m having trouble with third gear. I leave for work in the morning, shift from first into second, no trouble, then when shifting into third, it hard and if I try to force it in, it grinds. All the other gears shift smooth. What could it be, linkage, fluid, the operator. I even tried double clutching, it still wants to grind.
The bad news is that is that the answer to “what could it be” is none of the above. That points to a bad 3rd gear synchronizer in the transmission. This means a tear down of the trans.
The good news is that you can actually drive without 3rd gear. It can be annoying, but it works. How many miles are on it?
The car has 122,000 miles. The colder it is outside, the harder to shift.
You could try having the trans oil changed. As it gets older it doesn’t lubricate as well. When it is cold it is also thicker. The fact that the other gears are fine indicates that you do have something going on besides just the gear oil. But - getting fresh clean stuff in there could still help.