I’m guessing this is a Cobalt 1- the Cobalt 2 was a huge improvement as to speed and particularly the compass, if that is important to you. If you have the serial # we can say something about date and time of manufacture.
There were issues, particularly with battery door leaks in the early Cobalt 1, and rusting magnets in the keypad. Both are easily fixable and no longer a problem with updated parts. Atomic is extremely good on customer service. The recall had to do with tightening a stud nut on the HP side, if loose it could allow HP air to leak in and blow out the sealing O-ring. Few units were defective, and in fact most Cobalt 1 production did not fall under the recall. You can look on Atomic’s website and see if this particular serial number is in the group that should be checked. If the Cobalt passed the inspection it was supposed to get a new style cover to indicate it had passed. It’s also Atomic’s policy that if a Cobalt fails due to a HP leak, it will be repaired or replaced regardless of warranty status.
Overall reliability improved a lot with time in production. Like most new products, many changes were made to fix failure points that turned up in use. I think the fact that Atomic has been very open here about problems creates the impression that they were worse than they actually were. Most owners had no issues, and therefore don't post about them.
FWIW, Atomic will totally rebuild a flooded, out of warranty Cobalt with a new circuit board and bring it up to current assembly standards for $350.
If it runs, this sounds like a great deal. Can you see the unit? If so, check the System Info screen for atmospheric pressure to verify that the depth sensor is accurate. At sea level it should read near (plus or minus 20 mbar) 1014 mbar on average- depending on weather. Above sea level it will be less. If it checks out, I’d do it, then update the firmware to the latest version if that has not been done.
-Ron