The cell voltage was 2.74 V, now it is 3.23 V.
I just successfully replaced.
I followed your advice, using a second cell soldered to pins 4-8 of DS1210.
My wife saw me during the work and told me: you put it in extracorporeal circulation. She is a nurse.
I had several heart strokes (pin removed from the original cell, positive battery terminal near gnd and the like) but I did it!
At the end I drank a large glass of red wine.
Next replacement scheduled for November 9, 2029.