This can be caused by either build up of glue overflow around the nozzle or exposure of the nozzle to heat. In such incidences, remove the nozzle from the bottle and alternate the nozzle with the Nozzle of the Maverick Clean and tip the bottle upside down for about an hour. If the Maverick Clean is not available, push the nozzle from the bottle and soak it in acetone or nail polish remover (acetone based) for approximately 4 and 8 hours respectively.