Starting issues

hello everyone! First post. The starter in my 1974 Scamp cranks once but then it disengages and won’t reengage with the flywheel. I’m considering replacing the starter but I’m not sure if there is another issue that could be the issue.
Thank you for answering my question. I ordered a new starter. One of the mini starters from a Dakota. One of my friends said it could be A vacuum leak but when it would start it would idle & I don’t actually know how a vacuum leak would make the starter kick out. Again thank you I figured it was the starter but I wanted some confirmation.