Lukeman Exercise Two | Kelly Cannon

I read the section about the dash and parentheses because I don't have any in my work at all. Here is the original sentence:

"One such thing was the olive green washing machine. It was constantly breaking and Ben was constantly fixing it. It seemed that as soon as he got something fixed another part would break and he'd have to trudge down the stairs to the concrete basement to fix it. My uncles say you could hear him muttering behind the door of the basement. "

This is my revision:

One such thing was the olive green washing machine. It was constantly breaking and Ben was constantly fixing it. It seemed that as soon as he got something fixed another part would break and he'd have to trudge down the stairs to the concrete basement to fix it--muttering behind the door.

I really didn't like the sentence, "My uncles say you could hear him muttering behind the door of the basement." so I thought adding a double dash could fix it a bit. It sounds better and makes the idea sound more like apart of the rest of the paragraph.