Where can I download the C07.121 movement decomposition diagram? What is the reason why the movement of the watch is particularly low after the watch is cleaned? Do the plastic parts inside the movement need to be cleaned?
I have a lot of confidence in @Mark so that video section answers all my questions! Lube the automatic mainspring with Moebius 8200 and apply braking grease to the barrel wall. The 8200 will protect the spring and make it just slippery enough to help winding it into a mainspring winder without breaking. Obviously, the very thin layer of 8200 will not defeat the effect of the braking grease, or that is at least my interpretation of the video passage.
Nevertheless, I agree with many that the best path is to replace the mainspring if one is available when servicing.
Just curious; did you get a chance to look at the date wheel issue again? If so, I do hope you were successful in finding the source of the problem and can share it with us!?
The calendar works of the 2472 is the most sophisticated I've come across so far with its instant date change where the date wheel doesn't move one bit until it flips over in a blink. So fascinating I recorded a video of it here.
a new mainspring is always needed when doing a service/overhaul. new alloy mainsprings come with a dry lube so you may think they are not lubed but they are, . if you reusing a mainspring which i do not recommend then you have to clean off the old oil first if there is any and then use a piece of watch paper coated with oil then put it between tweezers and run the spring through it. I cant recommend an oil because i have never reused a spring but i can say it wont be 8200 since it is a natural oil and can spread and contaminate your barrel and movement. there really is NO reason to oil a mainspring except for maybe rust protection when dealing with very old NOS blue steel springs, or if the manufacturer specifies. I personally never oil automatic springs since most automatics i work on are modern and use white alloy springs, which again already come pre lubed. Some springs have a teflon coating which looks blue that will have to be removed prior to install to prevent emulsion from forming. Has anyone tested the power reserve in auto with dry spring vs one that has a lubed spring? Do that then decide for yourself