Philco 610 Tombstone: Hums but no reception?

Hey folks,

I am VERY new to restoring anique radios.

General question: What does it mean when the radio hums (from the speaker) but I am getting no stations to come through? All of the tubes work. What could be the issue? Is there a quick answer to it? Is it a capacitor issue?

Also, if a tube has a crack in it, does that mean that it is no good? These are not from the Philco model. Can I test my tubes with a multimeter? How?

Sorry for the elementary questions, but I have to start somewhere.

Thanks for the help and Season's Greetings!

Humming with no reception:

- LOUD humming indicates bad power supply capacitors. The ripple in the plate voltage would probably prevent reception.

- Soft humming indicates that you have both filament and plate voltages. Something is blocking the signal.

- Is an external antenna needed? If so, places to connect one are provided.

A cracked tube may have partially lost its vacuum. This causes the tube to conduct too much current, removing the signal. It also means the tube will fail shortly, as the air leak will eventually burn out the filament.