As far as I know, a more twisted cable is less susceptible to interference and probably the old YTKSY was screenless, and the new one? Maybe a professional
even grounded the screen

. This full synchronization may drop even further, and the improvement may only be deceptive after resetting the machine that determines the stable speed. Time will tell.
Pumping? In my region, bakers, builders, etc. work in this industry. I am a mechanic myself

and such various strange terms are used / invented and disseminated by them, in other regions this slang already differed in part. I haven't met pumping myself and I have no idea what it means. As for crimping RJ, it is a simple matter, but sometimes it will not tighten properly and there may be circuses, as well as there is no transition, it is worse when there is poor contact.