Why does the setting dial sensor seem bad?

The mode wheel usually consists of 2 or more metal fingers that slide over gold plated segments on a circuit board as the wheel is turned, so making contact with different circuits to select the different modes. To be realistic, your best bet is to put a watch on eBay for the same make and model of camera offered as “spares or repair”, but with a different fault. They go pretty cheaply. Practice disassembly on this, following whatever guides and videos you can find online. You should then be well placed to install the necessary parts (probably the entire top panel) on your camera with a spare from the one from eBay. If you like, you can then try taking apart the dodgey mode wheel from yours - it may be a destructive process - to see what’s inside and whether you might have been able to fix it, perhaps by increasing the pressure of the fingers or cleaning the tracks.

Remove the battery, then squirt some rubbing alcohol underneath the dial (wet a cotton ball with the alcohol, then squeeze it out inbetween the dial and the camera body, or use a syringe), or use a spray can of electronic contact cleaner. To make sure the rubbing alcohol gets in there, you can widen the gap between the dial and the camera body by inserting a fingernail inbetween, but don’t overdo it or else something might break. Once you’ve got the rubbing alcohol in there, rotate the dial a bunch of times to work the alcohol inbetween the metal contacts inside the dial mechanism to clean off what seems to be oxidation on those contacts. Apparently the contacts oxidize quickly—maybe the manufacturer “forgot” to apply a gold surface layer to them. After you squirt in the rubbing alcohol, wait about fifteen minutes before you reinstall the battery, to let the water in the rubbing alcohol evaporate, or else it might short out some electronics inside the camera and fry it. Preferably use 91% rubbing alcohol instead of 70%, since 91% will introduce less water into the camera. This process works for many people, but not everyone; when it does work, it might be only temporary for some people, at which point you can do it again.