Restoring a 301 non-strobe platter

When my Garrard 301 arrived, it was in a quite poor condition, but I was aware of that. As my time is limited in the moment, but I wanted to work on it, I decided to restore the platter first, as that seemed to be an easy task. But I was wrong. It turned out to become a real time-consuming task. First I stripped the black paint off, as the platter was resprayed in an unprofessional way. So far the easy part. The platter looked like this after the paint was off:
And from the reverse side:

The remaining spots where not paint. The platter was corroded under the paint. And at this point the nightmare started. I tried various metal polishes, lots of elbow grease. Nothing helped, the platter got better, looked shinier, but the countless spots remained.

As I didn't have too much time, the platter went to the storage in the cellar, a week or so later I started to polish again. That procedure repeated several times.
One weekend I did another search on Google: "aluminum cleaning". Various tips and recipes turned up. Like using a mixture of salt and vinegar to polish. Serious.

One of the recipes was using lemon juice. I gave it a try, like the salt and vinegar thing before. I realized that at least something was happening. But not enough. In my desperation I tried a few things in combination with lemon. What worked finally, was the following:

Starting position

Rubbing the platter with a lemon half for a couple of seconds


results in this


Now use a brass brush and loosen the corrosion:


Which looks like this then, as a result:


Don't try to weep the platter clean now, as the lemon juice is too dry and you'll just rub the loosened corrosion back into the metal. Use the lemon again for a few seconds


and then quickly wipe the juice and the corrosion off with a clean piece of cloth


which gave me this result

Amazing, isn't it? It took me about 2 hours to polish the platter to as new condition.