Sorry; I read that as the gun not opening to remove the barrels. I think anyone who owns more than two Parkers has one that does not want to break down. Sometimes a gun that has been regularly used developes this out of the blue.
For a long time I thought this was ejector related until I had a hammer gun act this way. I find that looking the other way when breaking down the gun sometimes clears it. On hammerless guns letting the hammers fall usually helps.
I still look on ejectors/extractors as the cause. When you get the gun open, remove the extractors/ejectors from the barrels, clean them well, and clean the pilot hole with Hoppes on a Q Tip.

Best, Austin

This is not unique to Parkers; I have a Fox that does this as well.

couldn' tclose the breech to fire the gun.

So you got the barrels off and hook out with no damage by taking out the screw?

PDD

I know the answer to that problem. If the gun has an automatic safety which prevents the gun from being dry fired with the lever over to the right, use a utensil of some sort to trip the lever, then fire the gun. The gun shouldn't need to be completely closed. Repeat several times if need be. Spray some kind of lubricant into the area of the cocking crank, which is the problem. Keep cocking and firing if you can, until the barrels free themselves. Absolute last resort is to remove the floorplate. I may have left something out of my procedure, but it has worked for me every time but once. I was so glad to get that one gun back together with the original parts that I can't even remember what barrels I was trying to fit to the gun in question. I never tried again.

Bill; It has been my experience that goo and oxidized oil and grease under the extractor/ejector causes a forward pressure on the roll. It is this forward pressure that keeps the cocking hook from disconnecting, not the cocking hook itself. I may be wrong, but cleaning the extractor/ejector mechanism has worked for me.

You are exactly right in tripping the Parker poker to release the hammers to fire in a gun stuck in open position.

Best, Austin