Hi Ray,
The RTC is a DS1307 with the small crystal (as in the picture in the build instructions http://rayshobby.net/wordpress/wp-content/uploads/2013/12/IMG_0003.jpg).
I read in another post (regarding the faulty chips) about shortening the connection from the crystal to the chip. I have mine soldered as shown in the build instructions but I could try solder the crystal directly to the chip if you think it’s worth a try?
My script seems to be working well so far so I’m not overly concerned at this point.