Mid 1800's Flintlock - Lock Question

[Limestone]

I recently got an old flintlock from a family member. So far all I have done is take it apart, wipe down metal parts will a light gun oil. Have reassembled it. The lock will hold at half and full cock. When the trigger is pulled it will not fire. Lock appears complete. If I pull back on the cock or hammer, and pull the trigger it will fire. Any thoughts on what I should look for to fix this? Not sure what type of musket it is yet. Was told it may be French. Not sure how to upload pictures yet. Thanks in advance

[John Holland]

Most respectfully, without photos of the inside of the lock at full cock it isn't really possible to properly answer your question. Some may speculate on what the problem might be, but that's all it will be, speculation.