Looks to me like you have the basic pot metal 3-shaft HL gearboxes. I've tried the HL 2.4GHz electronics on my Bulldog, which has 4-shaft steel gearboxes and 480s in it. It browns out running in the house. The same tank runs beautifully using Taigen 2.4GHz electronics. I think that HL took some steps backwards when it moved to the 2.4 GHz setup. The same tank ran well with the old 27 MHz RX-18s. Aside from losing the proportional speed control of hte RX-18, the new 2.4GHz setup also seems to have lost the more robust FETs of the RX-18s. If you have an RX-18 tank, try the same setup in that tank with the RX-18 electronics instead...or try a Taigen. The problem isn't the battery's capacity (4700 vs 1700 mAh).

Oh...those pot metal gears have a tendency to bind if not broken in. Recommend following the procedures in the FAQ sticky in this forum to break them in.