Brunswick Pot metal - preventative measures?

[VintageTechnologies]

I don't recall seeing any Brunswick potmetal falling apart. There does seem to be quite a variance in the quality of potmetal however. The earliest Zenith battery radios are full of potmetal parts that crumble to pieces; for that reason I have passed on those. I figure if a potmetal part has survived 90 years intact without cracks, it will likely remain stable in our lifetime. I have Fletcher reproducer on an Edison DD that I have been nervously watching for the past 40 years; so far, no cracks.

[De Soto Frank]

About three years ago, I acquired a decent Brunswick upright with the Ultona reproducer head.

The swivel knuckle was seized tight. I did not want to force or break anything, so I soaked the joint variously with Kroil, and PB Blaster... nothing worked.

Finally, I appealed to the collective wisdom here, and the suggestion was made to put the affected part in the freezer for a day or so, then trying to free it. This method worked.

Once I had things apart, I inspected everything closely for cracking / swelling / other signs of terminally-ill pot-metal. I did not find any.

So, I gently put the joint back together util things got tight, then backed it apart, and looked for "shiny spots" to indicate binding. I gently polished the high-spots down until things went together and worked smoothly. Then I lubricated with some petroleum jelly.

The machine is currently in storage, so I don't play it, nor do I see it often. When I do visit it, I move the reproducer joint, to check for binding.

If you do decide to sand / polish-down tight spots, proceed slowly and don't remove too much material, or you might end-up with air leaks.

A dry environment is also good advice; swelling and cracking is the manifestation of "inter-granular corrosion" in the metal alloy iself. This can be accelerated by dampness.

Good luck with your machine !

Frank

[Torjazzer]

Thanks to everyone for your responses. I think I'll keep checking it and rotating the face every couple of days. Whenever it looks like trouble is brewing, into the freezer we go; it seems like a popular fix. Dismantling seems like a last resort, especially since taking a Brunswick apart is a LOT more risky than fiddling with a Victor.