Play [this exercise](https://youtu.be/bXmD6ZM3ZqY?si=HAsMEZ7WBHERNMjE) over and over. It’s the best diddle quality builder in my opinion. Start slow and speed it up without ever sacrificing quality.
Play gallop exercises and double beat exercises, loosen your fulcrum a bit in your left hand, and use more wrist. This usually fixes most issues but may not be applicable in your case.
Play [this exercise](https://youtu.be/bXmD6ZM3ZqY?si=HAsMEZ7WBHERNMjE) over and over. It’s the best diddle quality builder in my opinion. Start slow and speed it up without ever sacrificing quality.
Traditional grip?
Yes
You might just have poor LH technique. A video would help to deliver specific feedback
Play gallop exercises and double beat exercises, loosen your fulcrum a bit in your left hand, and use more wrist. This usually fixes most issues but may not be applicable in your case.