This SL-1200 came probably with a defect in the tonearm tip, so the connector of the headshell is slightly rotated counterclockwise, it means the azimuth is not correct. In simple words, the stylus does not fall perfectly perpendicular to the vinyl surface, but is rolled aside. This means unbalanced channels and possibly vinyl damage due to the bad angle.
This was luckily fixed without any other tools than a phillips #0 screwdriver, because the 2 holes for the screws that holds in place the headshell connector are a bit larger, and allows a bit of play.
NOTE (1): in this case the offset was quite big, so after some research in forums I found out this approach. I believe that many arms are not 100% perfect, however headshells always have a couple of degrees of play when fixing them to the mount, if you have them slightly offset this can be enough. Other tricks consists in fitting a shim of paper or any other thickener between the headshell and the cartridge.
NOTE (2): I got that those screws must be TIGHT. Otherwise applying a bit more force than usual when mounting a cartridge will slide the connector out of the way, and it will became wobbly. However i don't know how much force the screws can hold before breaking the thread. I did it safely because I had a spare damaged arm i could have used to swap the tube in case of failure.
Pictures: [ Ссылка ]
*** If you want to do it, do it at your risk, this just shows how I fixed MY unit, it's not sure it works for others. ***
![](https://i.ytimg.com/vi/ccBXKsy-lt4/mqdefault.jpg)