A trader buys two July futures contracts on frozen orange juice concentrate. Each contract is for the delivery of 15,000 pounds. The current futures price is 160 cents per pound, the initial margin is $$\$ 6,000$$ per contract, and the maintenance margin is $$\$ 4,5004$$ per contract. What price change would lead to a margin call? Under what circumstances could $$\$ 2,000$$ be withdrawn from the margin account?