How many here service their own reels?
It has become my new hobby, and I am just wondering.
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.
Yes, is the (1) word answer, lol