You can easily check Ron's question by simply locking the toggle back, which takes the pressure off the locking block, and seeing if the rotating effort changes.
I've encountered this problem before. Here's how I fixed mine. Might or might work for you as well, I dunno.
With the pistol fully assembled, look carefully to see if the sideplate extension under the locking bolt is fully seated down on the frame. If so, and the sideplate and the locking bolt have different numbers then it is possible that the portion of the sideplate that the locking bolt rides over is a hair too thick. Or, it could be the locking bolt handle that is too thick.
Either way, you can carefully file a couple of thousandths off either that top part of the sideplate or from the underside of the locking bolt. Touch up with cold blue. It's often difficult to fit parts properly without sacrificing a bit of finish.
Also, with the sideplate, barrel, & barrel extension removed does the locking bolt then rotate easily in the frame? That is probably a good clue that you have an easily fixable tolerance stacking issue as noted above caused by mis-matched parts.
It COULD be the locking bolt spring is out of spec but I suspect otherwise, especially if the locking bolt rotates easily with the top half of the pistol off the frame.
-Bob
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