How to account for Election Judge (no w2) and additional federal withholding?

Yes, you are correct. You must enter this income under Other Income. To do so, please follow the steps below:

1. Open your return.
2. Click on Federal.
3. Click on Wages & Income.
4. Click on Less Common Income.
5. Click on Miscellaneous Income. Click Start.
6. Click Start next to Other Reportable Income.
7. Enter the description and amount.

Now, to report the withholding, please follow these instructions:

1. Click on Deductions & Credits on the left hand side.
2. Click on Estimates & Other Taxes Paid.
3. Click Start next to Income Taxes Paid,
4. Click Start next to Withholding not already entered on a W-2 or 1099.
5. Enter the federal withholding.