[NLRS] How to troubleshoot a flaky feedline?

[David Palm]

I'm reworking my antenna stack in preparation for this weekend's contest.
I was able to replace my broken homebrew 222 quagi with the K1FO-style yagi
I got from the W0GGM estate via W0ZQ and then WA2VOI (thanks men! and W0GGM
RIP.)  I'm not yet able to rotate the stack right now, but it's pointing
basically southeast.  Imagine my utter surprise when I turned on my
transverter just to check the antenna's SWR and I heard some modulation
near 222.100 -- tuning up a bit brought in N4PZ calling another station.
How often does that happen?

I have also put up a long conventional yagi on 1296 and a long loop yagi on
902 from the K0FQA estate (again, thanks WA2VOI! And K0FQA RIP.)  Those
aren't fully connected into the shack, but I'm a lot closer to having a
footprint on those bands.

Now, to the meat of this email.  My 144 MHz yagi has been showing highish
(is that a word?) SWR for a while now.  After the antenna shuffle I'm
seeing about 5:1, which causes the transceiver to fold back.  I've checked
and the antenna itself and the rotor loop are fine.  It's the feedline from
the shack to the rotor loop that's the problem.  Terminated with a 50 ohm
load, I'm seeing that same 5:1 on this feedline using my MFJ-259.  Wiggled
the connectors and didn't see signs of intermittent connections.  I did
some preliminary googling on how to identify where this fault may be and
came up empty.

Any advice on how to troubleshoot and repair this?  Obviously I can pull
and replace the connectors on each end, but since I'm not seeing obvious
intermittence there, that seems like a crapshoot.  Obviously I can just
replace the entire feedline, but I hate to scrap an entire length of
LMR-400 if some can be salvaged.  Ideas?

73,

David  W9HQ