Well, after 4 years and countless rounds, my P22 suddenly gave up on me at the range. Bummer...it was the only piece I brought that day.
Anyway, diagnosis was pretty simple: Everything worked except hammer, which would return of I applied pressure on it with my thumb.
A call to Walther (S&W) number listed in the owner's manual went well. I asked whether I should ship it back to them, was asked about warranty, and was told that it was out of warranty since Walther offers (unlike S&W) only a 1 year coverage. The tech, however, offered to send me a new hammer spring, free of charge. Yes!
Spring arrived four days later.
Taking the Walther apart was easy, albeit messy. Push two pins which hold action in frame, remove from frame, unscrew two screws (Phillips head screwdriver, a first one I saw on a gun), tap a little to loosen up the thousand-of-rounds-worth-of-dirt, pop the two halves apart. Hey, there is a spring flying somewhere and the never-used trigger lock part!
An half an hour on my knees and I found it.
Trigger, trigger bar, hammer assembly came out with ease. Push the pin in hammer out, slide the new spring in, push the pin back in. Okay, the spring is longer than it has to be and does not completely sit in its hammer cavity. The long leg of the spring does not want to stay where it should be!
I ended up taking the sear/sear spring off the frame, set the hammer/spring in frame, cocked fully, and then seated the sear/spring back into frame to hold hammer in place.
Next was to fish the trigger bar ears back in there, set it all on pin, and start messing with the trigger return spring (tiny and wanting to jump out). Next was the awful trigger lock, its tiny spring (which holds it in place) and much needed drenching the whole thing in Rem oil. Little compressed air, slap the other half in, screw tight (with blue Loctite) and back into the polymer frame. All in all not hard, but next time I'll be opening the halves inside a large plastic bag.
Sorry, no pics.