What is the test for a motion for a judgment of acquittal?

After the government had rested, defendant moved for a judgment of acquittal. The court denied the motion. Defendant then introduced evidence. However, he did not renew his motion for acquittal at the conclusion of all the evidence, as required by Rule 29 (a). His failure to do so operates to waive the benefit of the motion. This court, however, may and frequently does review the sufficiency of the evidence to prevent a manifest miscarriage of justice. Robbins v. United States, 345 F.2d 930 (9th Cir. 1965).