[gary rabbitt]

Hi Mike and welcome!

The B- can be different places in radios. Sometimes it's the chassis, other times it's a common point where the negaive leads go but not the chassis. Those are known as a floating ground. Check the diagram to make sure. ( I don't have it on front of me at the moment)

I just restored the chassis and phonograph of one of those models.
One note, the chassis is very tight and not much room to work in. I decided to gut the old filter cap can and install the new caps inside of the can. It would have been hard to install the new caps under that chassis. It looks totally stock, using the old can and cover, recrimping the can back into place.
Both of the IF cans I had to rebuild, because of the silver migration disease". I wasn't sure which on it was, so I redid both. If you have no symptoms, I'd leave them alone of course.

The connection to the speaker according to the instructions, is to 'see' exactly where the loudest peak of the signal is. Many of us don't use a meter and rely on the ear to get to the highest setting. I have a little meter just for that purpose, but I admit I use the ear about 50% of the time .
It's just a little millamp meter with a diode on one of the terminals. Your digital meter is just about useless for this purpose.

If you have any other questions about the chassis, I'd be happy to help.
Oh, one last thing, those IF cans have to be adjusted from both the top and bottom holes.
Good luck!