If you have not assembled a Tamiya gearbox you may not be interested in this post.
While assembling a Tamiya double gearbox I noticed the grease used between the axle and brass bushing was quite stiff. Enough so that the bushing wanted to turn with the axle.
Was I right about this. Perhaps a wee bit of super glue or even a bit of the grease on the outside of the bearing would keep it from turning in the case. Or may light machine oil to lube the axle.
I've started using very little grease with those gearboxes. I've also started using Tamiya Cermaic Grease instead of the stuff that comes with the gearboxes.