ETMX has some periodic oscillation. It's damping was found tripped this morning.
We tracked this down to the power normalization stuff that Yoichi added over the weekend.
With a non-zero normalization factor, and a small TRX transmission, the input the XARM controller gets really big. When XARM is then triggered, a huge impulse is sent into the SUS_ETMX_LSC input, which causes the Vio2 filter in FM0 to ring like crazy. This probably also explains why Yoichi was seeing trouble locking the arm when the normalization is on
The solution, as Yoichi also mentions, is probably to trigger the normalization like we trigger the rest of the boost filters.