When trying to restore a poorly cared for older record, this is what I have found works best. I clean the record with an ultrasound bath using whatever cleaning formula you prefer. I use plain alcohol and water per the Kirmus recommendation, and a few drops of Photo Flo surfactant. I find the Kirmus machine to be the best bang for buck if you are not a DIYer. Ignore all the steps, put the records in the bath and push the button.
Next give it a quick rinse with tap water and dry it. Now for the important part…play it. The stylus, especially the line contact variety, penetrates deep into the groove and will dislodge stubborn grunge (especially mold) that the ultrasound cavitations may not have gotten to. After a couple of playbacks reclean the record.
It is the post cleaning playback that contributes to the gradual, final restoration of the record.