There is a bar that is bolted to the top of the gearbox that is essentially a guide for the horizontal and vertical gear change cables, so the gearbox is in the central position when the cables are.
Toyota have designed a brass like perishable part which seems to wear over time. Both parts from my old and new gearboxes had considerable wear on them. But the good news is that you can do a quick hack to bring it back to new.
After removing the airbox assembly, and black gearbox supporting bar and the highest gear selector cable (which should take around 30 mins) you're ready to go on this hack.

Here is the bar you need to remove. The two bolts shown are the only thing holding it in. One of them should already be removed when you took the supporting bar off.

When you got the bracket off, turn it over and you should see a brass square component. Be careful as the brass cube is only held on by suction and may still be on the gearbox. Two sides will have considerable gouges in them and will create little play in your gearbox change.
Simply turn this brass square 90' so the fresh sides are now doing the work, and this will eliminate any slack you may or may not have. Remove the cube, clean up all working surfaces and grease everything etc.

The turned cube will be tight fit, but if you clean out the channel and use plenty of grease, then it's going to be feeling LIKE NEW as the brass cube is the wearable part and the guide on the gearbox arm will be unworn.
Re-assemble everything, start granny shifting, fast 'n' furious style (whatever that is)




