I need to ask a couple of questions
1. it is 1237 and NOT 1237a?
2. look at the bottom of the stock lug, it should have two eagle 6's
Its in rougher shape, lots of bluing loss, of course I would still buy it if the price was right
I will assume it is 1237, the firing pin being messed up by the factory is very unlikely - much more likely it got swapped accidentally by a soldier or at the company.
Grips should be marked 1237 - which is unusual, most lugers the only have the last two of the serial number.
1237 would have been made in late 1926 or early 1927 for the army - there were a total of less than 12,000 Simson lugers made. BTW, I have accidentally written Simpson - oh well