I purchased the tactical force tf5 mp5 style air-soft gun, and was wondering what kind of magazine fits it?

It came with a 500 round magazine, which suffered and unfortunate fall and is now broken, i have some "Well brand" mp5 mags from a previous (and fairly crappy gun) ,the mags fit but the but they wobble a lot. I look up the manufacturer and they don't carry extra mags, so all you airsoft junkies please help a newbie in the sport :) thanks