On a 1099R form that was a 401K plan the IRA/SEP/SIMPLE box is not checked. Is that correct?

Yes, that box on the 1099-R form should be checked ONLY is the Payer was an administrator for an IRA or SEP IRA or a Simple IRA.

A 401(k) plan is none of those.

What should I do if my 1099-R has that box incorrectly checked off for a 401K plan?

There is no box on a 1099-R for a 401K. There is a box to indicate if it is an IRA/SEP/SIMPLE only.  Do you have a question related to how something is being taxed?

Thank you! Form 1099-R most be amended.