Yesterday, the modified UIM coil drivers for ETMY and ETMX were tested in-situ. The transfer functions are showing an average drive increase of ~3.8 for ETMY and ~3.9 for ETMX comparing them before and after, which corresponds to the modification as described in T1400223.
A second test was carried out, using the monitor boards current channels. The test consisted in sending the equivalent of 1V to the coil drivers, to each of the UIM osem channels, and recording the current increase with channel ${QUAD}_L1_FASTIMON_${OSEM}. Jeff K helped me for the calibration of those channels.

The output voltage of the "fast current channel" of the monitor board as described in T1100378 is measured across the resistor Zout. The relation between the current and the ouput voltage is described in the last equation of Jeff's notes attached, with R1/R2 = 1/3 and Zout = 2010 ohms. In other words Current_readback_calibrated (A) = FASTIMON_Readback (cts)* 1/1638.4 (V/cts) * 3/2 * 1/2010 (ohms-1)

For ETMX I measured a transconductance of ~0.6 mA/V for each channel which matches pretty well with the design, but for ETMY it didn't quite match. First, only two channels (even though the mass was moving) were seeing a response, and secondly, the working channels were showing ~3mA increase for 1V drive. Since the transfer function shows that the driver is working as expected we certainly have something going on with the monitor board.

The non functioning channels are LL and UR osems. For UL and LR, when no voltage is sent to the coil driver, the readback sees ~4000 cts (as shown on the screenshot).