Is yours like this? (see the link below)
Like KE4AVB indicates backlash is usually not the answer.
Closely inspect/compare the forward gear and shift dog. Pay attention to the forward gear and the end of the clutch dog for forward. Mark them
BEFORE you lift them out so you know the orientation for comparison of the F/R en-gaugement ends. Usually you will find when comparing that the ends on the forward clutch dog and or the forward gear have worn surfaces like the video shows Also make sure all shims are in place so as the clutch dog gets fully en-gauged. The guy mentions such.
You probably know this but make sure that the brass bushing are properly installed so as they drop down fully into the housing. (they have a locating hole and pin to keep them from rotating.
Also while you have it apart check the outer AXLE bushings. They are usually worn out.
The inner axle bushing are the same type and are usually ok.
The outer BUSHINGS wear out due to poor design, lack of lube and dirt. They can be found at a reasonable price.
If your is like this one if you pay attention sometimes you can just flip the complete forward/reverse axle with the gears and the reverse side will pull ok forward but you have to hold it in reverse when backing up. This make the reverse gear and clutch dog the forward gears.
I've taken as many as 3-4 of those just to make one good one.
The you tube guy has a good tip about the grease. I usually just wipe out some of the worthless red clay grease (no need in trying to make a silk purse out of a sours ear so as to make it look pretty) and use EP#2 and add little bit of 90-140 oil in the center section. I also pay attention the to shifter shaft's forward groove for the poppet ball. If the edge or the forward groove is worn off it won't hold as well.
Also pay attention to the shims the guy mentions on the outer side of the forward/reverse gears. Too much end play slack of the F/R gears and the clutch dog will not hold as good.
https://video.search.yahoo.com/search/v ... tion=click