I have noticed that not all tippys have this problem. My one friends custom didnt wobble at all, while my other friends and mine did. Not much, but just enough to notice and annoy.
Its a very simple mod! Simply remove the one half of your marker. Then take out the front grip. Put one layer of electric tape around the circumference of the part that is under the hole that the screw goes into yet not low enough for the gun to show. It is the perfect width for the standard roll of electric tape. Place the grip in the half and then place the other half on top. Screw it together, and NOW THERE is no wobble.
***Please note*** - You will not be able to slide your grip in and out now once you remove the screw you will have to place it in your gun and then put the half on it, and remove the one half to remove it. Not a big deal at all.