I have used pressure pliers for a couple years just adjust them to grip the nipple, and the flickering has always been a telltale signed of bulbs dying, if they start turning off it is time to change cos any day they will die.
Bare in mind that ur headlight magazine might be stuck due to mud (dust and water) or other debry so applying some remover or oil b4 attempting to twist the poorly designed tit and special tool, bcos otherwise if too much force is applied it will brake (as it has happened 2is to me). If that happened get pressure pliers and lock them on the remaining of the tit and twist carefully in a circular motion, not jerking it much, remember the housing is only plastic and it brakes. This is what i have been doing with mine for the past years. Next owner, if ever sell, is gonna get the pliers with the treg xD.