Rust removal...?

Rust = corrosion, which will get worse over time. That said, the watch is nine years old. How much more do you want to invest in it?

Baking Soda + Lemon Juice paste . . . dab some on the rusted spot and leave it for a bit before wiping away with a damp cloth.

I’d just clean it off with a toothbrush, use a light touch with some polishing compound and call it good.

Well, I am not sure if ALL of it is rust. Some of it might just be grime. But I plan to pass down all of my watches to my children, so I'd like to keep them all in good shape, with proper maintenance. The watch wasn't expensive (my wife paid $69 for it, in 2014. We have a rule about not spending over $75 on gifts for minor holidays and occasions. This was a Valentine's Day gift.) The watch has been repaired 1 time, when a steel ring on the dial came off, and got tangled on the minute hand) for a total cost of $45 ($25 to fix it, $20 express shipping.)

Thus, I currently have $114.00 invested in this watch. Considering that I have worn it as my daily watch for as long as I have owned it, I'd say it has been worth the amount of money that has been spent on it up until this point. I suspect the jeweler might charge between $25 and $50 to clean it, since doing so will probably require removing the stem. So if it does cost $50, then the total investment will have been $164.00. I don't think that's too much. Especially considering that I probably won't need to spend anything else on it (aside from replacing the battery every 3 years or so, which is no big deal.) Now that it is on a NATO strap, I don't think it will get as much bodily oils on it, as it did when it sat in direct contact with my skin.

@SNWatchNerd and @ThirdWatch : I would love to clean it myself, but the problem is, to get to the part of the case which sits behind the crown, I'd have to remove the crown. I don't feel comfortable doing that.

If they want an outrageous amount I’d love to help you out. Shipping would probably be a pain though.

Option 3: Do it yourself.

You can take the crown out, it's usually a little tab that you press or something similar where you see the stem entering the keyless works. Pretty simple. But if you don't feel comfortable doing it, a dab of some Naval Jelly should take care of it, provided the base metal is ferrous. Take care to not get any inside.

The suggestions by @SNWatchNerd & @ThirdWatch are good options too.

The question is also why it rusted in the first place. Do you store the watch in a humid environment or do you suspect this to be due to your own sweat?

Also, who tightened the case back and scratched the case?

Either way, any rust protectant (CLP, etc ) will take care of it. I would agree that removing the crown is best.

Toothbrush and cheaper white toothpaste, not the expensive gel type. 4.99+taxes. A toothpick is good too. Scrubbing patiently required...

It was never stored anywhere except my sock drawer (before I had my jewelery case) or in my jewelery case, after 2015. It must be from sweat. Or maybe water from the faucet. I have washed my hands many (countless) times while wearing it, but I usually take care not to get water on the watch itself. Perhaps a drop or two escaped my notice.

Scratches on the caseback: It was either from one of the times I had a jeweler replace the battery, or it was from when I sent it in for service. I myself have never attempted to remove the caseback.

My guess would be one of the times it's been to the jeweler. I doubt very seriously the people who make the watch wouldn't know how to properly remove the backing.

I never noticed the scratches before. Thanks for pointing that out.

Seeing as how the watch is 9 years old, I guess I'm not that mad about it; we all get a few bumps, bruises, and scars during the course of our lives. 😎 I guess heavily used tools are no different. 😎 I'm going to chalk it up to "scars give it character." LOL 😉

I'd pull the crown out and clean it, using not a tooth brush but an inter dental brush.

You mean just out to the 2nd position, where you set the time? Is an inter-dental brush that small?

Yeah👍 inter dental brushes are very small start at 1mm

You paid to have a Sturhling serviced? Seriously?

I wouldn't even pay for a battery change on one of these.

The toothbrush/toothpaste will do fine. It is a $50 quartz watch. Unless it has significant sentimental value, hard pass on paying anything to have any type of service done on it.

Well, I have heard a lot of negative things about Stuhrling, but as far as my own experience goes, the watch has worked well for 9 years, and still looks beautiful. And you're correct, it does have sentimental value; as I stated above, it was a Valentine's Day gift from my wife. I have better watches in my collection, but the two watches my wife gave me (this Stuhrling, and a Marc Ecko "Encore Oz" fashion watch) both hold very special places in not only my collection, but in my heart also 😀

The reason I give Stuhrling a little slack is because on the opposite end of the spectrum, I have purchased products in the past (I won't bother naming them here, since they aren't watches) that were supposedly high-tech, highly-engineered pieces, that turned out to be "meh," at best. So I was pleasantly surprised to find that my Stuhrling, which seems to be ill-thought-of in general among watch collectors, has actually turned out to be a nice, long-lasting, reliable watch, and in my opinion, fixing it one time, for $45, in the span of nine years, is no big deal. 😀 But, to each his own. 😀 Your mileage may vary. 😎👍

Now that makes sense. Glad it has given you years of service and in the case of the sentimental value, I would try cleaning it myself first, gently, and then consider having a watchmaker clean and service it.