Help with a Zenith Please?

[Hullblazer]

Right.  My father bought a bag of 35 watches and inside it I found this.  I know nothing about it except it is a Zenith Automatic SS and that it works well, except for the second hand having fallen off.

Can anyone help with an actual model name?  A year? 

Also, I'd like to get a peek at the mechanism but I cannot fathom the access to it.  The only case opening accesses the face and the winder is completely enshrouded in the case?

[jdm]

In the Mark's video section, check "how to open a watch without a case back". Sorry I don't have the link at hand.

[Hullblazer]

That's more helpful than you'd think - thank you!

[oldhippy]

Could you show the back of the watch please.

[WileyDave]

Do I win anything? Just kidding...

https://www.1stdibs.com/jewelry/watches/wrist-watches/zenith-stainless-steel-automatic-wristwatch/id-j_1662363/

[wls1971]

Hi the watch you have is a model that was produced in 1965 as part of a range of watches to celebrate Zenith's 100th aniversary and is referenced as a model A6621 and should have a caliber 2542 PC within the case. The zenith employee's making this watch at the time nicknamed this watch the "Schlusselloch"  the "Keyhole" I have no idea of production numbers but should imagine its quite uncommon

[wls1971]

I forgot to mention the case is a two part case,the movement is held in place with a retaining ring around the dial and is fitted with a split stem to allow removal from the front.

[Hullblazer]

Thank you all, that is all Brilliant!  I'll post the rear pic tomorrow.

[Hullblazer]

12 hours ago, oldhippy said:

Could you show the back of the watch please.

Sorry, this is the only one I have at the moment!

[oldhippy]

Thanks. I see wls1971 has answered your question for you so you shouldn't have any trouble. Just remember some two piece stems take some pulling so just be careful.

[jdm]

Seems in pretty good shape, beads of rice bracelet and all. Personally I would leave it undisturbed unless you have a compelling reason. Even polishing and servicing the movement is better left to a future buyer, they often whine about these jobs not done correctly unless they are done by a recognized professional.

[vinn3]

when you don't have a seam at the case back it is usually a "front loader" with a two part stem.    the stem part is removed and the mvt. comes out from the front.    vinn

[Hullblazer]

Yay!  Thank you all!