I've been poking around with a Certina cal. 25-651 for some time now. When putting the last piece together, the date wheel mechanism, I realized the date disc was not moving no matter how many times the hour hand went around.  I started looking into the problem and soon realized the date wheel, 2556 had a broken spring. The "hook" on the spring was missing. Googling the problem revealed two things: a.) the spring is fragile and my problem is a common one with this calibre b.) The