The GPS at 200m has quit reporting. It died around 01:00 UTC, April 27.

I noticed 200m was an outlier in the "chronyc sourcestats" output on flux. This listing shows an offset of 1051 microseconds for 200m instead of +-4 microseconds for the others:

chronyc sourcestats
210 Number of sources = 6
Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
==============================================================================
50m                        39  21   10h     -0.000      0.001  -2198ns    13us
100m                        5   4   68m     +0.002      0.124  +4085ns    27us
150m                       32  15  534m     +0.000      0.001  +2403ns    11us
200m                        7   4  103m     +0.058      0.024  +1051us    16us
250m                       43  21   12h     +0.000      0.001  +1879ns    12us
300m                        5   3   68m     -0.001      0.145  -1918ns    31us

The serial port doesn't show large values of fe (framing errors) or breaks:

root@200m root# cktty 3
3: uart:XR16850 mmio:0x10000000 irq:122 tx:1936 rx:808452280 fe:24 RTS|DTR

I don't think power to serial port 3 can be controlled with "tio 3 1/0". When I tried to power off the GPS on 150m, the output to "rs G" did not stop.

As a workaround, I edited /etc/ntp.conf on 200m and added 150m as a server. So there is no urgency to replace this GPS.