Open assessment VS Practitioner Open assessment

I am preparing for PSM I certification. I read everywhere that we need to pass Open assessment with a score of 100%, which I do regularly. I also try the Practitioner Open assessment which is more difficult. I can't get more than 93%, even after 20 attempts. I have an idea of the questions I have problem with, but since there is no feedback one the test is passed, it is very difficult to learn what I am missing.

I have two questions. How necessary is it to achieve 100% on Practitioner Open assessment to have good chances to pass the PSM I certification? And, any clue how to get answers to the Practitioner Open assessment?