Copying old cassette tapes

I am using version 2.3.3 on Windows 10. I am digitizing some homemade cassette tape recordings from the 1980’s and 1990’s. They have deteriorated somewhat. I’ve gotten pretty handy with using noise reduction to remove the hiss of the tape player, but I still have one problem. Near the beginning of some of the tapes, there is this wave effect, like the music is pulsating from right to left ears, like you you almost can feel the tape going round and round. This usually gets better within the first minute or so into the tape. Is there any way to correct for this?

Mix to mono will remove all stereo effects, be they deliberate or accidental.

Thanks so much for this tip about converting to Mono. This was the perfect thing to use on the next cassette I converted.