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
Should be easy for you since you did auto mechanics. The hardest part is making a proper diagnosis as to what is wrong. Regular maintenance of degreasing a reel and re-oiling or greasing is rudimentary for most. It's getting the right parts and at a fair price w/shipping that is important if you need to do a repair. Most reels that are reliable to start with need very little maintenance for years of trouble-free service if you just fresh-water rinse after every use.
I have Penn GS reels over 20 years old that I still use with no problems that use the HT-100. And of some of those older than that with bushings, like a squidder/jigmaster that I rarely use any more, they will outlast us all! For big spinners, the only two I have: Penn Spinfisher 9500 and Shimano Baitrunner 4500 BR series are basically indestructible.
Changing the drag stack and choosing the right grease for a "wet" or "dry" drag is probably the most involved repair. It's not bad if you get the order and direction of the drag washers correct.
For bait-fishing, I would really say a conventional over a bait-cast of about a 15 size for over-all pier fishing. It will last longer and have less problems/maintenance over years.
For someone that is an occasional fisherman, you'd be surprised, any decent moderately priced 1 rig could last a "lifetime" in example: a size 15 Squall and a Tigerstik.
Alan, I think that is quite common with low-profile reels (especially used in saltwater). I am seeing that people will buy something like a $100 Daiwa Fuego and just replace it when it goes out. That is why I haven't really bought low-profiles for casting lures. That is where I will buy a spinner of 2500 or 4000 size and use it to cast lures. The 1 Shimano 1 piece casting rod I have, I will throw a 6500C3 (not the best for anything light-weight lures much below an ounce and not magged) for the few times I might try it for a heavy salmon lure. None of the round reels cast lures much better no matter how much you spend.