Hi ,
You should be able to see the firing pin protruding from a small hole in the middle of the forward face of the breech block.
It's possible that it's broken, but it could also be quite dirty in there. You'll have to disassemble your Luger to check on it.
There are instructions here:
http://lugerforum.com/lugerparts.html
Be sure that the gun is unloaded, and that you check the chamber before you disassemble it. A loaded luger can easily fire when it's disassembled.
Your gun may need cleaning and lubrication most. The Luger is a very tight tolerance firearm, and just a little dirt can get in the way...
Marc
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Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.