Did they solder the crystal's body to the board?The datasheets for the crystals I bought said specifically *not* to do that. The heat of soldering can crack the crystal.As I recall, the boards I used kapton tape to hold the crystal closer to the board perform slightly better.
I use a small drop of gel-type super glue to hold the crystal to the board. Then I solder one lead at a time, with a micro alligator clip on the crystal lead as a heat sink, and taking care not to heat it longer than necessary.
This sounds like a reasonable (and effective) installation method.
After my supply of 1307s run out, I'm done with them. I'm going to use DS3231 moving forward.
Are there any alternatives to the DS1307 that operate at both 3.3V and 5V and are available in a through-hole package?