Omega Cal. 1020 supposed to click when setting time?

I recently had an old Omega cal. 1020 automatic serviced. Since coming back from servicing, it makes a clicking sound when setting the time forward (see audio file.)

I'm wondering whether the clicking is the expected behavior for this movement or not. The 1020 has an odd (and rather annoying) day-change mechanism – setting the time in reverse also advances the day of the week (the date is set in both directions by turning the crown in position II). I'm assuming the clicking is related to the day change mechanism. It always makes a clicking sound when setting the time backwards and advancing the day, but it's never before done it when setting forward. Quickset day/date and midnight rollover appear to be working fine.

Can anyone else familiar with the 1020 advise as to whether it's supposed to do this when setting the time forward?

The Clicking Sound (AAC)

The day also does not set backwards on mine. Setting the time forward makes the clicking sound, but does not affect the day or date. Does yours make any sound at all when setting the time forward?

I did some testing over the last couple hours, and I'm also noticing a significant inconsistency regarding the midnight day/date rollover. Previously the rollover would completely right around midnight. Now, it seems to complete somewhere between 11:55 PM and 1:30 AM, seemingly at random. Occasionally it doesn't seem to be completing the rollover at all (until the mechanism re-engages around 9:00 PM the following day).

Reading around, it seems like it could be an issue with the tension on the cannon pinion. Apparently this is very tricky to adjust properly on the 1020.

I have a one-year guarantee on the servicing, so I guess I'll just take it in again tomorrow. Hopefully a quick fix.