Intermittent Spark on left side with new coils

[Zippo]

Hello darlins'... nice to see ya. It's been a looong timmmeee. Anywho. I have been trying to diagnose my 82' xs400 intermittent spark issue. I keep dropping a cylinder after the bike sits for awhile. I replaced the old battery that was over charging, the coils and spark plugs. The carbs have been gone through dozens of times and sometimes if I jiggle the wiring harness I get the coil to fire in time but it always skips a fire here and there. I feel a rewire is in order but can I just replace half of the harness as the right side fires perfectly. I will attach a video so you can see with the timing light what I am talking about.

 

[Revvy Kevvy]

It has to be only connected to the ignition system so this is basically 12VDC to a coil and then a set of points (contact?? dunno what you call them in Portland we call them points) so if it aint the transformers then that leaves the points not opening or the 12VDC missing from the system on that set of points.

Timing light...no, it ok on the other side.
Transformer...no, thats new.
Points (maybe, there are two, maybe its not opening or its really dirty. maybe try the same idea but put a LED light across it with a 350R resistor and see if the points dont operate sometimes.
Cabling issues on the low voltage side...maybe, I found a few on mine.

But, listening to your video I dont hear any missing, it sounds all ok to me.