Hello all, I keep getting a gun sent to me because the gearbox is seizing up. Every time I take the gun down (Echo 1 G36, stock) and pull down the AR latch, the gear box unlocks, I test fire it and it seems fine. When ever I send it back to the owner, he uses it for less than 20 minutes before it seizes up again. Obviously this is pretty frustrating for both of us. So I've got two questions: 1) Could this be a voltage/current issue? I'm testing the gun on a 9.6v 2200mah battery and it is working fine. The owner has the stock 8.4v battery and it locks up. Or is this just coincidence? 2) If it's not a voltage issue, what is it?