The bubble walls are made with extremely fine holes or actually a porous material - making a fine mist of bubbles. Believe it or not, a pin make extremely large holes - in comparison to the general porous material. Whenever air can escape from an easier/larger place rather than be forced through a smaller hole it will. The air will always go out the larger holes now - and not out the smaller ones.
If you were to poke more holes along the bubble wall that match the larger holes you made in the one spot - evenly distributed all along the wand, you will get large bubbles that are relatively symetrical along the length of it. But you will probably never be able to get the fine mist of bubbles again with that wand. Replacement is your other option.
When a bubble wand cloggs from algae, one of the easiest methods to clean it is to rub as much off as you can with an aquarium cleaner sponge and then soak in hydrogen peroxide.