Groove Juice. You can buy this from Audiophile for 400-500 pesos. It works wonders for hardware. It removes grime and rust in a minute, but it will not patch up corrosion pits... re-chroming ang solusyon dun.
TIP: Never use it on cymbals (like what it's meant for), because if you read the label carefully, it's made for brass, not bronze. Your cymbal will discolor and you will form a frown in disbelief.