Double Bell (TM) Desert Eagle cycling fault.

[PReDiToR]

Hi, I'm new here! <waits for applause to die down>

I bought this gun from boneyard hoping to get a £130 pistol for £30.

I ran a few BB's through it yesterday and pulled it apart to see if something jumped out at me.

The mag inserts, seats, feeds fine. The slide is pulled forward with enough force to have everything in battery. The trigger pops the hammer, the valve releases the gas, the hop throws a BB out through the barrel, and the slide goes rearwards ... And that's where it goes wrong.

The slide cycles limply a few times without firing a BB, then I have a gas spraying disappointment in my hand. I assume this is from cooldown.

The culprit seems to be the valve knocker not returning with the slide cycling. The trigger bar is worn to silver, but doesn't look bad enough to need replacing (I could be wrong, I'm not an expert, so I've included pictures).

To forestall a few obvious things:

I'm on propane in a new mag, everything is lubed enough.

The hop is applied.

The barrel is clean, the hop rubber seals, the nozzle, slide, trigger, and hammer move freely. The knocker moves freely except when it's stuck in the forward position, which I'm pretty sure it shouldn't stay in after the first shot.

Pictures are of the knocker with the hammer cocked, and with the hammer down. I've tried moving the knocker into the correct place manually but it seems to be catching on something. I don't know enough about this system to confidently say where or how it should sit, and what is stopping it, this is just my guess from knowing that it shouldn't be at rest depressing the valve with the hammer back. This is why I'm asking you, the kind people of the t'Interwebs for your help and opinions.

More than happy to test anything you need to know. Thanks for any help offered.

Worst case scenario here is I replace the trigger bar, then the hammer, then the other little fiddly parts until it works.