There are some zero amounts on Federal, and the system says I can file by Mail. Yet, I don't get a print button, and it keeps going in a loop.

Please try this printing option:

Please log back in your TurboTax account and "add a state" to open the return back up (you are not really adding a state, just to open it back up), then select Tools on the left, Print Center and choose the print center, then select returns and choose to print just the tax return or to include all worksheets as well.

If you are still having printing issues then please see this FAQ:

https://ttlc.intuit.com/replies/3301671