[Chris Radek]

If it was 1-4 I would think it's asking which year of the leap cycle you're on. 1-5 I have no clue.

I looked through my set of 70s-80s "Technical Letters" but only found instructions for series 228 (the one with one button and one knob that pushes and pulls). It does not know months at all, and you have to correct it on short months.

 

[Chris Radek]

Are you sure yours is not module 254 or 255? 229 had two buttons.

 

[Chris Radek]

I know this is going to be a pain and might cost you a whole set of batteries, but would you try something? Set the watch to mystery# 1, Feb 28 11:58 PM, then mystery# 2, Feb 28 11:58 PM, etc., until mystery# 5, and in each case let it roll over past midnight, and see what date you get after Feb 28?

 

[Chris Radek]

Ooh I think I get the prize!

Will you do the test I suggested? (I don't understand why 5 instead of 4 but maybe you'll break the code if you test it!)

 

[Chris Radek]

That's the point, we don't know! But if you set it to 11:59pm on 2/28 #1 and 2/28 #2 and 2/28 #3 and #4 and #5, and then wait and see what date comes next, you will have data that might help us understand the function.

Then you might want to see what comes after 12/31 #1 through 12/31 #5? Maybe you will find it has a 4-year cycle that makes sense. Or maybe you will find a deeper mystery, or just despair! Who knows?

If you collect all the data I think we can reverse-engineer the function of it. (This is what some of my friends call a "geek trap")