This is a good lesson for those who still think playing Mono LPs with a Stereo Cartridge, even with a MONO switch somewhere, is as good as a true mono cartridge.
That was me until I tried the advice here, and found a true mono cartridge, can be a bit, some, a lot, a whole lot better
Some Mono LPs, I purposely listen from only 1 speaker which takes away the habit of my brain’s seeking imaging.
blessed be my McIntosh Mode Switch

I started with this basic Grado Mono and found it was better than using any of my Stereo Cartridges, as I say, the reduced noise and distinction of individual instruments improves, sometimes dramatically.
https://gradolabs.com/products/grado-prestige-mono-phono-cartridge-model-me
Jim brought part of his collection of Beatles, 6 LPs: 3 Albums, both Stereo and Mono LPs, we had a good time listening to the differences.
Several friends who heard the differences here subsequently bought Mono Cartridges, I now use one I had VAS build me, an AT33PTG/II MC Mono Body I bought broken, rebuilt with a Line Contact stylus on Boron, always ready to go in seconds on my 3rd arm. I have a lot of Mono, mostly Jazz, some purchased, most inherited.
The recording skills were very good in the late 40’s, early 50’s, but as now, the results captured varied.
here’s a broken Mono Cartridge that VAS could do something with, and you end up with something otherwise unobtainable
https://www.ebay.com/itm/205973558658?mkrid=711-53200-19255-0&campid=5338381866&toolid=10001&customid=a3e6a6ea-ea52-11f0-98cb-326537633663