Brand new first motion shaft all standard A+ gearboxes. This gear was used in all standard A+ gearboxes up to about 1996, and has 17 teeth and has one groove cut into the center of the teeth. Certain SPI cars and all MPI cars used a 16 Tooth gear with two grooves (DAM6242). The 1st motion shaft serves as both fourth gear as well as the transmission input shaft, and receives a lot of abuse. If a bearing in the gearbox fails then this shaft can get destroyed quickly. 
 
Often times a crunch while engaging a gear is a result of a failed synchro ring, however if left ignored the gear and selector will start to get damaged. If you see any chipping or broken selector teeth, pitting on the synchro surface, or any wear on the actual helical teeth, it is time to replace the gear.