Prewar Junior mainspring different to postwar?

[ggggr]

Got a sweet prewar tin grip junior in a job lot. I changed the main spring and now it won’t cock?
I dimly remember the prewar springs are different to the postwar? Am I right? Feels over sprung.
Cheers Paul

As the thing was working with the old spring, the chances are the sear is ok.
Im guessing it is probably the little cocking shoe that is worn.
If you have another pistol, take the barrel and linkage off that to try on the one that isnt cocking. If it then cocks, it is probably the cocking shoe.
If it doesnt cock, try the mainspring in the other pistol.
If you dont have another barrel and linkage to swap over, then you can reverse the cocking shoe (Hoping it hasnt been reversed already) . Its sometimes easier to take the pin out of the bracket on the barrel and turn the linkage over (which will reverse the shoe), rather than try to remove the cocking shoe pin.