Answer:
Though blind as well, can lead the blind well.
You heard me before, yet you hear me again, then I die. Until you call me again.
Used on a diamond and left on a board. It's great for a gymnast his grip to restore. What is it?
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
It can cause deflation of tires when dropped from the rear of spy cars.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?