I had some vaguely similar problems with my LSD2, and they ended up replacing the caps. I'm not saying for sure that is your problem, but I had similar unpredictable waveforms. A capsule is a diaphragm and backing plate with 48V charge across them, and the sound pressure effects this capacitance (bad explanation, but bear with me). If there is a tiny piece of dust or some moisture in between those plates things like this will happen... at least that is the explanation I got from the Studio Projects repair folks.
In your case, it's going to be trial and error, and swapping.
a) Setup in living room and reproduce problem.
b) Swap mics where they plug into cables (swap Left and Right), wait for it to happen again.
c) If it moved from L > R then it must be in mic body or capsule. In that case swap capsules (Left and Right) and see if it moves with the cap, or stays with the body.
d) If it didn't move after swapping the mics at (b), then it must be cable/preamp. Swap cables and see if it moves. If it does, it's cables, if it doesn't it's preamp...
Hopefully the problem isn't horribly intermittent and you don't have to wait for days for it to happen again.