[NostalgiaRadioTime]

Finally getting around to giving a 41-255 I picked up over 15 years ago the proper attention it deserves, and have a bunch of questions I'm hoping those who are far more knowledgeable than I might know the answers to.

First, it appears that the first pushbutton on the left was originally supposed to be to turn the set on, is that correct? Someone soldered the button lever tight so it cannot be used, and on my set, the first knob on the left is for tone, and the second knob from the left is off/on/volume. I'm thinking this should just have been a volume only pot. Here's a pic of the soldered lever:
   

And here's a pic of the off/on/volume switch:
   

Second, tube talk. This set uses two 7A4 tubes in place of the XXL's that the schematic calls for. Are these suitable replacements?

It also uses a 7C6 in place of the 7B6, and a 7B7 in place of the 7A7. Do these replacements work as well as the tubes that the schematic calls for?

Lastly, I touched the center pin of the volume control with a screwdriver and got loud volume, so I know that part is good, but I can only get the local station faintly at full volume, even with the antenna connected. There is a wire on top of the variable capacitor that wasn't connected to anything:
   

I wasn't getting any sound without it connected. When I connected it to the lug opposite it on top of the variable capacitor, I got the station faintly:
   

But I think there must be something missing there that I'm not finding on the schematic. Just a plain wire (with that great dried rubber insulation flaking off) can't be all that was connected between there? Should there be a capacitor up there?

I know these probably are dumb questions, but I am just a novice here. Any thoughts, ideas, help would be greatly appreciated!