[Eliot Ness]

Scott, sometimes the conductive layer of a pot just gets worn away and all that can be done is to replace it.  Some of the pots are wire-wound and not subjective to being worn away and respond better to cleaning.  For lubing a pot I like to use Deoxit Faderlube.

Hi Henry, I'm still learning my way around.  Could you please help me understand which one(s) you are talking about?

Henry is talking about the 4 areas I have circled, they have a thin mica sheet under the adjuster.  It's hard for me to tell if they were damaged but I don't think it would cause a lack of total reception if one or two were slightly damaged:

   

The 24 lights up, but not the 224. :-( Here are the notes from the seller:
One is a National Union NY-224 type 24A vacuum tube, and the other is a Philco type 24.
These tubes tested GOOD on a reliable Hickok Model 800A tube tester (a dynamic mutual conductance tester).    ... and NO shorts or gas detected.
They both had readings of 600 micromhos.  These tube are right at the minimum, but should still be usable.
Ref:  Minimum readings should be 600 micromhos (60%) and new tubes should test at 1000 or more micromhos.

I wouldn't make it a habit of buying tubes that tested that low.  Measure the filiment pins of that 224 tube and if it measures open I'd make the seller replace it.  If he balks at your request file a Not As Described claim with eBay.