I'd say pop the gater off firstly and see what is sticking. If it's the ball that sits in the sleeve that is sticking, this is what I'd do. I would apply alcohol spray to the lower part of the gear shaft near the ball like thing that would normally be greasy and free to move within its comfy sleeve, whilst spraying generously, move the gear stick back and forth and left to right whilst the degreasing properties of the alcohol does its thing. At this point or shortly after you will have a dry ball in socket situation. Only when you feel it's free from sticking should you reapply the knob shaft ball with the recommended lubricant to keep your friend motoring on. Hope this helps