Why does Stacey’s wool jacket become a more emotionally charged symbol as the plot unfolds?

It becomes an emotionally charged symbol when He gave it away to cunny T.J and uncle Hammer seized the opportunity to teach him some lessons about life.

Explanation:

Stacey's wool jacket was a gift that was handed to him by Uncle Hammer. Stacey's parents were of little means so the expensive jacket though a little oversize got the admiration of all in the house including Stacey himself. But when they went to church and T.J., his friend saw him in the jacket, he covered his jealousy by taunting Stacey, telling him that he looked like a preacher in the coat. Stacey who was intimidated by this later gave his coat away.

When Unce Hammer learned of this, he was angry but used the opportunity to teach Stacey that when he had something good, he should never be intimidated by others or convinced to give it away. He maintained that T.J. should have the coat since he knew its value and was able to make Stacey give it away.

i believe it is he has been given the drum as a joke.