Not unusual to have the first spring bar being engaged (round or trunnion bar) to require a little more lifting force than the remaining spring bar.., and it's more noticeable if the TT tongue jack isn't extended enough to relieve some of the load.
I would not recommended to have different chain links "under tension" to address the dissimilar lifting force required to initially engaged a spring bar.., because it's my understanding that once the tongue jack is fully retracted the pair of WDH spring bars tend to equalize their share of the load for proper weight distribution and support of the loaded tongue weight...., especially while the TV/TT is in motion.
As far as the same side of the TT A-frame always reflecting the higher spring bar lifting force, it could be attributed to a number of things (I'm thinking out loud here);
* The relationship of the spring bar to the side of the TT A-frame.
* The relationship of the draw bar within the receiver pin box.
* Design of the ball mount.
* Elongated hitch pin hole in the receiver pin box do to the use of standard hitch pin (inside radius wears pin box clearance hole).
* Ball mount wear at spring bar contact points.
* No two spring bars are totally identical (?).
Also, it's good practice to use the same spring bar in the same side of the WDH ball mount to minimize the wear of the corresponding metal parts.