you can use those marks to set & align the MhZ dial mechanical Stops on the drum

I did mine a few years?ago and dont remember it completely. you only need to make the adjustment if the Mhz is off. my radio was off by 1 Mhz, i had to set the Mhz dial either 1 Mhz higher or lower than what i wanted, (I don't? remember is mine was high or low) if your is off you can adjust by losing the screw that holds the drum to the shaft and make the adj then re tighten the screw

there radios are great receivers for AM shortwave and AM MW. a bit wide for ham radio SSB but still works if the bans are not to crowded