My DF Ginyu's left armguard (not completely the left entire arm) also fell off before. Simply pushing back into place didn't work, but what I did that finally got it firmly in place was I twisted the armguard left and right while pushing it into place. So far it hasn't fallen off again. If you'll notice the left armguard of Ginyu, there's some kind of imperfect mold/crack that seems to be present in all of the DF Ginyus that I have seen so far on the net. That crack must be the cause of the imperfect fitting and that's why you have to twist it left and right while pushing it back in to make it stay in place.
Which Frieza Soldier appeared in the anime again? The purple or yellow haired one? I don't want to buy both of them lol