I printed for four hours yesterday and didn't see any temp fluctuation issues. But then again, I'm probably not dialed-in enough that two or three degrees of fluctuation would be a big issue for me. However, I did I did a bit of Google research on the temperature fluctuation issue and found this statement at
https://www.jozerworx.com/creality-cr-10s-c4-capacitor-diy-fix-tutorial/:
"This issue is specific to the CR-10S. There may be other issues that affect the regular CR-10, but the regular CR-10 uses a different circuit board and will require a different modification. Any CR-10S using the Version 2.0 circuit board is affected by the bad C4 capacitor issue. Other CR-10S board revisions may be affected, I have heard conflicting rumors. As of February 2018, it seems like most of the CR-10S printers which have been sold to date include the V2.0 circuit board. As time goes on, Creality may begin selling printers with a fixed circuit board, but these will likely take some time to filter down the distribution channels so you will be at risk of receiving an affected printer as of this writing."
I don't have a 10S, just a CR-10. When things settle down, I will probably do the fan upgrade for the reducing noise levels....and will check the screw terminals, etc. in the control box.
FYI.....I didn't want to print a"cat" for my first work, so I did four of the gigundo bed leveling knobs. I got about half way thru the first layer on bare glass before things got "loose" on my first attempt. So, I did the hairspray thing.....and subsequently printed four of them w/o any failures. Precision on the parts seems pretty darn good, they snapped onto the existing leveling knobs w/o any issues.
Only problem is stringing. With 2mm retraction on prints #1 and #2, I had quite a bit. 4mm retraction on #3 was a bit better. 6mm retraction was good (not perfect, but almost) on the last knob. That seems like an excessive amount of retraction so I probably need another parameter to adjust. But then again, I'll be switching over to PET-G soon and probably won't use PLA much in the future. I don't think that PET-G will have the issue since I only use 1.2 mm of retraction for my other printer (using 3.0mm instead of 1.75mm filament) for PETG without
any stringing.