Is your image centred?

Since I've set up my table with the Mint, I have very centered imaging. I have been in the live recording studio, and attest that singers are in a booth. Their performance is carried on an individual track and in the mix, is positioned in the center of the orchestra. If your image is moving around, it's a fault and I would look at your setup. You say the Grado is the biggest culprit..probably the Grado is off "perfection" the most.

Stringreen,

I agree with you regarding most every classical LP I own, which isn't much, and with jazz. But with most other recordings (pop/rock/country) this shift in image and soundstage happens most often. Usually it is done as a gimmick. At least that is what I experience, even after Minting.

What you describe is normal and is what a good system should do. If everything was to the left or right then you have a problem.

You cartridges could be magnetized and or you could have a loose wire or connection on the turntable at the cartridge end or the interconnect end.

I would demagnetize the cart then clean the connections to make sure they are good and tight and treat with Pro Gold or other. Also, stylus wear could be a problem or VTA or Azimuth could be off. Last if you are using a tubes in the phono section they could be weak tubes too.
That's just my opinion.

I agree with both Stringreen and Dan_Ed. Most pop music recordings are multi-miked, multi-tracked and mixed (up) in post-production engineering. The end result is typically an imaging and soundstaging mish-mash, and the better the playback system the more obvious these engineering manipulations become. This is one reason we dislike most popular music recordings. If you listen on anything more resolving than a 1965 AM car radio, they sound completely fake. (Singers who can't sing are another reason, but that's for another thread!)

Good classical, jazz, folk and blues recordings are another matter. They provide solid, pinpoint imaging that stays put - assuming your components and setup are good of course. (I wouldn't bet on a Grado for imaging or soundstaging though. Accurate reproduction is not what Grado's are about.)