Since nobody seems to have made an alog, here it is.

We've steered the JAC transmission beam into HAM2 and removed the viewport cover on HAM2 on the +Y side to look inside. At first we had a hard time seeing anything. We steered the beam in YAW and PIT and still nothing.

After a while we found that if we position the IR viewer at a specific position and look into the baffle hole of the MC refl periscope (circled in yellow in the 1st attachment), we can see some kind of ugly IR that definitely comes from JAC, but no beam seemed to be coming out of the baffle hole.

2nd attachment shows the picture shot by an IR sensitive camra when we focused on the IR, and the 3rd attachment shows the same picture shot from the same position but focused on the  baffle.

The distance from the sensor to the subject according to the lens' indicator was something like 4m for IR and 1.5-2m for the baffle. The indicator is only good for visible light and not for IR, but empirically the scale is not a factor of 2 off for IR, so we're looking at something that is far from the baffle (i.e. we're looking at the image of the source reflected by the periscope mirrors).

Another possibility that Masayuki points out is that it could be some IR beam (probably not the main beam) hitting the vertical metal pillar of the periscope behind the bottom periscope mirror and we're looking at that through the space between the baffle hole and the periscope mirror (see the 4th attachment). I think that unlikely because the pillar is merely inches away from the baffle and the distance indicator of the lens doesn't agree. But we'll see.

Tomorrow we intend to remove the septum window cover for IFO REFL and POP and look into HAM2 from there, that way hopefully it's easier to find where the JAC beam lands in HAM2.