Second Casio ARW-32'0 at home

Today I've received my second Casio ARW-320! I thought only one on my box was not enough so I've look for another one :)
This second watch is not working properly. The digital module seems to work great, but the analog module doesn't run. The second hand seems to move but it does not advance, so any other hand is moving. 
I hope a good clean of the module will solve the problem. If at the end I'm not able to solve the problem I will have a lot of spares for my working ARW-320. 
Both are the orange button version... so now I need the yellow version one :)