ETA 2836-2 Date Change

[Dico]

Hello All,

Im working on an ETA 2836-2 installing the hands for hour/min/sec. As I usually do I pull the crown out and rotate a full 24 hrs until the date clicks over (midnight) and then install the hour hand. Then I do the same for minute hand to make sure hour hand is installed center. I have done this dozens of times usually with no issues.

On this specific movement however I have found that after installing all hands and rotating 24 hrs a few times to check accuracy of install, the date keeps flipping over earlier an earlier, about 5 minutes earlier with each 24 hour revolution. The hands are set well and not hitting anything or slipping on the hour or canon. 

 

Any ideas what this could be?

[rogart63]

I should say slipping cannon pinion. But you have already checked that? As  you wind it around something in the  date mechanism is slipping for sure. How does it feel when you set the time with the crown? If it's very light or heavy?