[time-nuts] Garmin 18x GPS WNRO, revisited

[Rich Wales]

I have a Garmin 18x LVC, connected to a Linux system via a serial port
on the motherboard.  Ubuntu 18.04.3 LTS, gpsd 3.17, ntpsec-1.1.0+419.

I bought this GPS in 2009, and it's worked just fine until earlier this
afternoon.  At around 2019-11-26T00:00Z, the GPS jumped back 19 years,
to 2000-04-11.  The time offset reported by cgps is 619,315,200 seconds,
or 7,168 days.

Is there any feature in gpsd or ntpsec which would allow me to fudge the
time value returned by the GPS to make it usable again?  Yes, I realize
it's not feasible in general to make gpsd deal automatically with every
GPS unit's unique week number rollover situation, but I'm thinking more
in terms of a command-line configuration option that can be set for the
specific piece of hardware in use on a given system.

Failing that, is it possible to flash this with new firmware?

Or has my GPS become a paperweight?

Rich Wales
richw at richw.org