The IC-7760 recurrently stops answering CI-V a few minutes into a network
session while the transport keeps chatting — pings answered, session alive,
commands unanswered — and the only recovery was the 30 s watchdog's full
teardown. At 10 s of CI-V silence the pump now says 'open' again on the
existing stream, which is all it should take if the rig quietly closed the
data flow; the watchdog remains as the backstop. The send counters gain a
mutex since the pump now transmits too.