Importing vinyl LP's, sound breaks up on playback

I’m using a Mac Mini (2010 model) with OSX 10.12.6 Sierra, and 4GB of RAM, and Audacity 2.2.2

I was importing several LP vinyl records and converting selected tracks to mp3, all successfully …until now! Project Rate = 44100 Hz. Now, for some mysterious reason, importing to Audacity appears to be working well (sound wave appears fine), BUT after completing the import, when I playback the recording in Audacity, the sound breaks up so badly the music is unintelligible. If I export selected audio (to mp3 file), it too is broken up and useless.

Why should this be happening all of a sudden? I haven’t changed anything (to my knowledge) since the successful recordings. Earlier, I had been using Audacity 2.2.1 but when I started experiencing this breaking up yesterday, I checked this forum and saw there was a new version, 2.2.2, available which I immediately downloaded and installed. Unfortunately, same problem. I had some success after powering off the computer and starting fresh, but after doing one LP successfully, the problem has returned.

My phonograph is connected via my stereo amplifier, using standard RCA audio cables, with an adapter inserted into the Audio IN jack on the Mac Mini. This has worked fine until now. I have no other apps running while using Audacity for these imports.

I welcome any tips (in “layman’s terms” please!) to correct this problem!! Otherwise, I like Audacity very much. Seems to be well-designed.

Try the suggestions in this FAQ.
– Bill