All 8 of the photodiodes in the photodetector array check out electrically. This was done using the diode tester function of a multimeter. Initially a problem was thought to exist with 2 photodiodes - top row, right most two - but this was traced to a problem with the cabling. The cabling was measured with the TDR, which seemed to indicate that the problem was either at the flange or on the in-vacuum side. Thinking that the seating of the PEEK 2-way coax cables was not good enough, the in-vacuum cable was removed and reseated (thank you Mitchell). The TDR yielded the same result. A check of the 2 photodiodes with another set of cables indicated that the photodiodes were good. Looking at the in-air cable, which was removed and reseated, two of the connections came good. The entire cable assembly (S/N S1301015) was replaced (with S/N S1301016) and all connections tested okay. Re-doing the diode test measurement confirmed that the 2 diodes initially thought to be suspect were okay with the replacement cable. J. Gleason, P. King