I haven't done anything internal to my Ticas, except a 5-y salt Libra SX3000 I'm planning to rebuild with new IAR clutch and CRBB.
(OK, I replaced a worm-drive bushing with a bearing on Libra SL)
The Cetus was my first reel after long-term Penn 4200SS (+4400SS), and it was shocking smooth and tough compared to that. So my reference point, especially in the size, was Alcedo Micron, and Cetus blows older reels out of the water.
The only weak point on Cetus for me is the hex shaft v. handle threading into main gear. Tom mentioned the stiff bail spring, but I'm 100% manual bail, and like a stiff bail spring so it won't snap on the 4-lb test during a cast. If you check recent Shimano, even with auto-bail-closure, the spring is so stiff, they won't close on auto-bail - you just turn the crank until you hit a brick wall.
If you look inside a Daiwa, their gears look like Tica's, and not without accident (except Tica gears are phosphor-bronze).
If you look inside Shimano, the fine-toothed gears look more like a watch.
Nobody does smooth like Shimano, but they didn't get to my tough-level until the big gears in '18 Stella, and every reel that has copied Stella since.
You also haven't described a specific gripe about the Cetus, so could only guess your complaint at this point.
I just finished customizing Paul's Samira Extreme 2000H, and I had previously customized one for me that I picked up at loss-leader Amazon half-price.
I noticed Paul's has more intertia in the worm gear than mine does.
Also noticed my low-grade SL worm drive moved like a tank until I lined the reel, and certainly there were tight bushings that needed to be loosened by wearing-in.
Also typical of Tica, I got perfect line lay on my new Cetus, even with 160 yds.
and at least part of the reason we ended up with a thread titled Libra, what they do with improved locomotive drive, aluminum frame and long-stroke spool comes together just right on the Libra SX.