2 Questions on early Marlin 336 - with pic

I recently acquired this 1949 336 in .32 Special, and noticed when I got home that the hole above the 2 aperture sight screws on the left side of the receiver is empty. On my other Marlins lever guns there appears to be a pin or something similar in that hole. As I look at it closer, I am guessing that is something that rides in a grove on the left side of the bolt, but don't know that for sure.

Q1 - Is my gun missing a part, and is it safe to shoot with this hole empty?

Q2 - It has the old style pre-1957 thick hammer. Is there a hammer extension made for these older guns, or some other way of being able to cock it with a scope mounted? I hope replacing the hammer is not the only way.

Thanks for your help!

Thanks all for your help. I'll get the part ordered. After doing a search for early 336 hammer extensions over on Marlinowners.com, and finding lots of info, I've decided it's better just to put a Lyman aperture sight on it, and pass on the scope. I have a scoped 336 .35 and a .357 94, so on this one I'll go with the improved iron sights. Thanks again!

Thanks for the additional comments, suggestions, and links! Back in the 70's I decided every deer hunter should have an iron sighted rifle for hunting foggy mountain mornings, when a scope was less than worthless. For a while I filled that need with a tip over mounts on a BAR, but was unimpressed and decided a seperate rifle was the way to go. I went with a peep on a Rem 742, and killed two deer with it.

Since I have a scoped 336 and a 94, I believe I'll go back to improved iron sights on this .32 Special as my fog rifle. The Williams aperture sight is on sale at Midway for less than $30, so that's what I've decided to do. Thanks again for your helpful suggestions.