Help please!! Mazda 1988 Won't Go Into Reverse??

I just replaced the clutch plate on my Mazda 1988 B2200, and I can easily shift into gears 1-5 but I cannot go into reverse. It will not even engage, as if I'm hitting a wall. When I removed the shift lever to remove the transmission I made sure it was in neutral. Can anyone offer any help? It would be greatly appreciated!

Pull the shifter lever and make sure all the dogs are showing one gap all the way across. I know you made sure of some things taking it apart but it sounds like your reverse dog is pushed out of line with the rest.

How would you gain access to those dogs? Is that inside of the transmission?

Pull the shifter lever from the top of the transmission.