Unless you are very interested in and equipped to attempt the component level repair yourself, just buy a new power supply it’ll be way cheaper than paying for someone to repair the old on.
With regards to surge protectors.
It would be better to say some protection is better than none. There are many good write ups on the subject.
Firstly there is a difference between "surge protection" and "voltage fluctuation". For "voltage fluctuation" one needs a power conditioner. Consumer grade "surge protectors" do not usually include power conditioning (cleaning dirty erratic power).
Secondly even the most expensive breaker box level whole home surge protection systems aren't 100% guaranteed to always work. Even less so the cheap consumer grade units.
Lastly all electronic components are a lottery. There are sometimes millions of tiny components. If any one of them is sub par, or the solder joint just wasn't quite right, it can cause a failure. Sometimes these failures take time to manifest, sometimes they are immediate. Surge protector isn't a panacea and will have no useful impact on a manufacturing defect.