There's lots of great suggestions.
When you say "It has a slide plate," do you mean it has a drop-in or top-loading bobbin? On those drop-in bobbins, the little spring in the front gets bent, or the bump that hits the spring gets scratched up, and then it makes a rhythmic thump, thump, thump with every stitch. You can take care of that by gently smoothing the bump with a very fine sandpaper (400 to 600 grit). It only takes a few strokes, so don't go too far. And the spring can sometimes be bent back in shape. However, if the bobbin case or spring are too damaged, they will need to be replaced.
If you have a front-loading, oscillating hook system (like in the picture above), sometimes a piece of a broken needle (or some other thing) will get embedded in the "race" (the ledge that the hook sits on), and make a terrible racket. Sometimes it's too small to see, but you can feel it by running a big pin all the way around the race. If you find something embedded in the race, you can use a small screwdriver or a big pin to remove it.
Another noisy thing that happens with an oscillating hook system, is that the hook driver gets loose. Then it bangs against the hook with every stitch. You can tell if it's loose by removing the hook, and pushing the driver at both ends with your fingers. If it's got a wiggle, that's something you don't want to try to fix yourself -- that's something for the tech to fix.
I hope you're able to quiet your machine, so you can keep on sewing.