I've been servicing my own reels for years. Spinning reels nowadays, as they are uncomplicated and you can often swap parts. Conventionals can be tricky and unwitting booby traps. I advise anyone just starting out to take apart the reel inside a large cardboard box. That way you don't spend hours on your hands and knees, crawling around and searching for a pawl spring launched across the room. It's a good idea to have several jars in which to safely store components. Also, take a picture of each piece you open, including all the screws. It will make re-assembly so much easier. Best of luck to all who endeavor. I am using some of the same reels I bought two decades ago.
There are a lot of YouTube videos on how to disassemble, service and reassemble fishing reels.
Some are done well and by experts.
However, there are also some who say they have been doing it for 20-30 years, yet use a water pump pliers (commonly known as channel locks) to loosen screws that are called "finger screws" and only require a ¼ turn with a flat screw driver. Another YT poster used an adjustable (commonly known as Crescent wrench) to remove a nut!
I don’t even like to use those tools on plumbing jobs, if I can help it.
“There is a right tool for the right job”.
So if there is an interest here, I can post and share some tips on how I do it.
Not how to service a particular brand of reel, but rather general tips to make it more efficient.
Also share some of my mistakes that I since learned to correct them.
I have found that (when everything goes well) while I am concentrating on the work (similar to fishing), it becomes somewhat therapeutic.
I just serviced one of my first spinning reels that could be (45) plus years old.
I like doing it myself and have for many years now. Especially drag replacements and or upgrades. Dennis with 2nd chance Tackle has a fantastic channel for complete breakdown and reassembly. He's got something like 700+ vids now over 3 years. Primarily conventional but spinning as well. https://www.youtube.com/channel/UCbNyOpdEZDO6H93bLm6lP9w