Hi and welcome! The problem is more likely to be the clutch than the gearbox. This problem is quite common and most people who are familiar with A10's will try to engage neutral as you are coming to rest, not actually when you have stopped. The A10 clutch is a bit crude, particularly the 6-spring, and whilst the 4-spring is much better it is still far from perfect. You need to spend quite a bit of time with the primary cover off, making sure that the plates lift off evenly and you need to have the minimum of slack/wear throughout the clutch operating mechanism from lever to the pressure plate to make sure you have maximum lift. A further problem is the design of the levers on A10's which have a short distance between the pivot and cable nipple; this gives good leverage but poor travel. Fitting non-standard levers gives additional travel. At this stage I would concentrate on the clutch plates and general efficiency of the lifting mechanism. It is worth checking that the lever on top of the gearbox is in its most efficient position, i.e. passing through a right angle as it travels, or as close to that as you can get. Good luck.
