1. Emphasizing the explanation:
* "She explained how to operate the machine, but I'm still not sure what the problem is."
* "She explained the operation of the machine, but I'm still unsure of the issue."
2. Focusing on the problem:
* "She explained how to operate the machine, but I'm still having trouble with it. I'm not sure what the problem is."
* "Even after she explained how to operate the machine, I'm still experiencing a problem. I don't know what's causing it."
3. Using a more direct question:
* "She explained how to operate the machine, but I'm still having a problem. Can you help me figure out what's wrong?"
* "I'm still not sure what the problem is with the machine, even though she explained how to operate it. Could you clarify?"
The best option will depend on the specific context and what you are trying to convey.