Gun won't reset to single action.... HELP

[dullone]

Took my 1977 p64 out for the first time today. Shot 3 mags and had this problem every shot.
Chambered a round, de-cocked it, raised the safety and fired in double action. The gun ejected the spent casing and chambered a new round, BUT the hammer was down, not cocked. Gun could be fired in double action after this and the same thing would occur, eject brass, chamber round but the hammer is down. In 3 mags did this every time. No FTFs or FTEs.

When cycling by hand it always resets to single action. SEE UPDATE BELOW

UPDATE......sitting here cycling the gun I find if I rack the slide quickly and let the slide slingshot forward the hammer won't set in single action but follows the slide forward.

Only thing I've done to gun is swap out hammer spring for an 18# Wolff

[fully machined]

Here’s a check that would leave out a slide /safety barrel to disconnector problems:
Remove slide and grips.
First, with the hammer down, push down on the disconnector to the frame. You should be able to “mash” and the disconnector go down and up without sticking. A real loose fit here. Slop everywhere, but the disconnector in the up position should not be holding the sear forwards.
A sticking disconnector, down, not returning, can cause what you described. Pushing the disconnector down a little, the pistol will not engage the single action.
Cock to single action and pull trigger and catch hammer letting it lower while keeping trigger pulled all the way back and hold back

Now with trigger still back push down on the disconnector until even with top of frame and release. You should hear a “click’, the trigger bar drop down and return, and the sear go back to rear.

With trigger still held down, you should be able to cock the hammer to single action and the disconnector should be free to move up and down.

[dullone]

Think I've found the problem. Not enough engagement of the hammer/sear interface.
The gun had a scary light single action pull, seemed like just the lightest touch on the trigger would drop the hammer. If you push up lightly on the hammer in it's cocked position it overrides the engagement of the sear and the hammer drops. I'm sure the hammer rebound after being driven back by the slide is enough pressure to override the sear engagement.
Pity cause the gun was accurate, even shooting only in double action.
Goes back to J&G tomorrow to get resolved. Gun was in really good condition, which is why I chose it over other that looked rougher.

[fully machined]

Sending it back sounds like the best idea. "Scary light single action pull'' -----Well let me just say this: about the lightest of any stock pistol I have ever had and I do not hand the pistol for someone to load and fire without first saying something like that.

[dullone]

Fortunately I live in Prescott where J&G's store is, so when I run some errands tomorrow they'll be on the list.
Actually I'm fortunate to live in Prescott for a lot of reasons, it's a great place to live. The only time I had a problem with one of my Ruger pistols I just took it to the Ruger plant here and problem was taken care of. Did I mention Davidson's ( big western gun distributor) is located here also. You can order through their website and take delivery at a local FFL of your choice and there are no shipping or transfer fees involved, and Davidson's give you a lifetime replacement warranty on any gun from them. Didn't know any of this till I moved here. Dumb luck
Yes Life is Good.

[dullone]

Update: Back from J&G with a new gun in hand, all is good.

[Curly1]

Good deal, I luv happy endings.

[dullone]

Took the new gun out, found it's a shooter too !!!!!!! But does it sling the empties!
Replaced the hammer spring with 18# Wolff and find the double action trigger pull to not affect my aim. Don't think I'm going to replace recoil spring as I don't find recoil objectionable.
Ran 50 rounds of Brown Bear and Silver Bear FMJ & HP without a hiccup.