Garmin Edge 830 elevation issues

Hi all,

I've used a Garmin Edge 830 for several years now with very few
(if any) real problems, but the last couple of rides the altimeter
has gone crazy.  It takes the elevation for its stored home
location (692 ft) just fine when I start the ride, but then it
starts climbing on its own and then descending--with no reflection
of the real elevation.

Here's the profile that shows for the ride today (FWIW, I never
saw the unit display anything over the mid 900s)...

https://ridewithgps.com/trips/207523646

and here's the proper profile from the route...

https://ridewithgps.com/routes/47703480

Anyone seen this before or have suggestions?  And no, I haven't
tried resetting the unit yet, but do plan to.

--
Ted Heise      <theise@panix.com>       West Lafayette, IN, USA