Hi to all! Without the pistol in hand, I'm not in any position to bark! But I can at least whine a little that maybe on the mainspring as being the issue, you're barking up the wrong tree?...
.... Even a pooched out, clipped .30 luger mainsprings will initiate closure from the full tension position! The only thing it won't do, is fully close?
So, in the event that the toggle stays stuck in the full travel position, it has to be an interference or lack of available tolerance at that position? So, here's the protocol for that check. First, strip the upper barreled receiver completely. Completely strip the breechblock as well. Now, if you install just the stripped breechblock, it should slide freely from front to back without ANY interference! Any felt interference will be multiplied when operating dynamically.
The measurement between the forks should be .715" ... Also, with a caliper, measure across the chamber, and also measure across the rear receiver forks, and they should be the same.. .939" usually? With the rear main pin installed, and just the breechblock in the receiver, put the abbreviated top end back on the frame, and close the take down lever. Now, everything, the receiver, the breechblock, and the the receiver with the breechblock installed in the frame should slide effortlessly back and forth.. Somewhere in all this, you will find the issue. I'm still betting on a coke bottle shaped crushed or twisted receiver fork will be the culprit??? BTW, try the receiver assembly on a known working Luger? That will tell you a lot as well... best of luck, til...lat'r....GT....
