Robert Crumb trying to melt his 78 record in the oven, trying to solve the same issue you've mentioned. As noted in the originating post, melting your record back into shape is "a difficult process, and one that can easily destroy the record as well." Here's another technique for using a hair dryer to more carefully heat a 45 back into shape. The process looks like it may take awhile, but appears to be more of a controlled process than Crumb's easy bake oven technique.
If the record is just barely warped, Pro-Ject's Record Puck can be a quick fix. The solid brass puck weighs 1lb 12oz and eliminates resonance caused by a warped record for non-spindle turntables.
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