My most recent restoration project; an RCA Model 224 from 1934. I purchased this fine piece for $25 in working condition, but needed the usual TLC. It was originally purchased from California Phonograph on Market Street, San Francisco. I got it with the original paper work, including the user manual.
Here is a look at the back before any work.
New chassis cushions. The originals were smashed one quarter of their original size. New cushions brought the chassis to the correct height and isolated it from the cabinet.
Those round rubber things, which have many names, but we'll call them chassis cushions. They play a major role in your radio's performance. First, they align the control shafts to the cabinet holes. Second, they prevent microphonics and third, they allow air flow.
Old cushions are just that; old. They are dry, cracked and in many cases, just plain rotten and squished down to flat.
New cushions are availble online, selling for around $20 per set of four. Don't forget about shipping and waiting.
Here's an idea discovered by KS6H. Go to $ Tree and buy a jumbo rubber eraser. Using a hole saw, cut the size for your particular make/model radio. Lightly sand and paint if you're picky. These work for a fraction of the cost and will last longer than gum rubber. See the pictures below and wonder why you didn't think of this.
Here is a look at the chassis before any work is done.
CAPS, CAPS AND MORE CAPS. These things were nasty looking and probably had lots of leakage. Never the less, taking no chances, they all got replaced.
It's finished, it works and everyone is happy. Listening to AM and shortwave is fabulous.