Thanks for responding. I checked the spring. Although it's a bit weak it does the job. I replaced the trigger and side plate with parts that work in another pistol but it still malfunctions.

yes Walt, that is the locking bolt ( I call it the takedown lever). If you can easily rotate that lever back over the sideplate, then it may be too loose. I wouldn't bend it too much at first, I overdid the first time and couldn't rotate it at all.
Jerry

P08 Trigger Problem Solved
 

Thanks to all of you folks I figured there should be no gap between the side plate and slide. If I pretend I have 3 hands I might be able to eliminate the gap thusly: 1. Press and hold the side plate against the slide as hard as possible to eliminate the gap. 2. Press the muzzle toward the back of the pistol. 3. Slide the locking bolt up 90 degrees to lock the side plate in place.
4. Dry fire the pistol over a dozen times without a miss. Problem solved.

Glad to hear that you found/solved your problem. What you described as to how to place the side plate, put rearward pressure on the muzzle, then rotate the locking bolt by 90 degrees, is the standard method of reassembling a P08. I am not sure what you did differently before. Anyway, enjoy!!