mazdatweaker
+1y
Whatever you were told by that person is wrong.
I have already told you the simple thing to check.
The reverse fork and 5th gear fork are inside the main transmission, and they share the same actuation rod.
The shifter has a ball with a pin on it that goes into a socket.
You take it out, and look into the hole to see if all the parts that it would intersect are in correct alignment.
Internal to the transmission, when you push the shifter to the right to attempt to engage reverse, there is a spring that should compress from the shifter input. Do you feel that resistance when you attempt to place the shifter into reverse?
There are three receivers on three rods inside the transmission. {1-2} {3-4} {5-R} If the shifter was pulled without it being in neutral, there is a really good chance that one of the rods is not centered correctly, probably the one that drives 5th gear.
You might be able to rachet it back if you pull the shifter out of the top of the transmission and verify things.
Anything beyond this will probably require transmission removal. I have heard you can pull the tunnel back to work on the actuators, but I have a lot of experience and it isn't something I would even go near.