Confusion reigns
I want to research the details on a new to me watch. So building on my previous post I started:
The watch to be considered is an "Elgin", pendant set, open face, in a yellow metal case. The white face has Roman numerals, a single sunk second hand and is marked in script "Elgin". The movement is marked "Elgin Watch Co", "USA", "Safety Pinion", and has a serial number of "7436989" There is engraving on the Regulator.
The case is marked "Keystone Watch Case" , has a keystone emblem with " C O" superimposed inside, a set of balance scales, and "Guaranteed", " J Boss", and "20 yrs" below which is a serial number "2906880". The case has a few dings and scratches and is missing the bail.
I looked in the big book ( CPGTW 2006) and on page 205 found a picture that was close. It's a model 20 in grades 571, 572, 573, 574, 575, 616. But, on page 200, the grades only go up to 416. Stumped I turned to the internet, and on the Elgin site, I ran the serial number and came up with "Grade 157, manufactured 1895/8, 7j " It also said, "16s of 3/4 pend model 7" which I first assumed meant 16 size, 3/4 plate pendent wind. The stumper is the model 7 as that list on pg 202 as a lever set 18 grade 265 with a date of 1897.
Could that that really mean ... pendent model, 7j ???
BTW the watch runs and keeps good time in the stem up position, but stops after a few minutes in the face up position. Could this indicate a problem with the hairspring???

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Pic 2

Your watch is a 16 size 7j pendant set. The grade 57X series is much later and much different. Elgin carried model number according to the size so you could have a model 5 16 size and a model 5 18 size and this would be true for the 0/6/8/12 sizes. I think the online decoder that says it is a 16s 7j pendant set is correct, the time mentioned sounds about right for the style.

If the hairspring was messed up, it is unlikely to run at all in any position. Running in Pendant up but stopping in face up means (at the least) that it needs cleaning, lube and polishing the balance wheel pivots.

Thanks guys, I really appreciate the help, I got a lot of learning to do.

Jerry, With IHC185 why bother learning the "hard way", we always are ready to share our thoughts.