Quad is Syma X5C-1. Mode 2. It does NOT have altitude hold. So, I need to hold on to the left stick in order to maintain the altitude. Trouble is, I can only maintain the altitude for a second or 2, the darn quad will go up and down whenever it wishes. At first, I supposed it was too light. So, I added some weight on its belly. That's not it. Is there a trick to this? I have been practising indoor for sometime now. I get to be quite OK piloting my quads, but they all have altitude hold feature except this one. I know how to trim, but that does not apply to my problem at hand.