Holdopen or lack thereof...

[Pappy]

Hi Folks.
I have a 1939 42 that functions perfectly except last shot holdopen. It will hold back about 20 - 30 % of the time.
- I use three mags;
original and two MecGars, all with Wolff extra power springs.
- Ammo is Geco 124 gr, WW 115 gr.
- masking tape cuts on rear of frame shows toggle comes all the way back.
- Pistol is clean and oiled.
- Pushing upward on mag base does not help.
- Holdopen will work 100% by hand cycling on empty mag.
- I have bent holdopen spring down and no effect. Note: spring was not that springy, but bent easily.
- grip does not rub against mag button.
- new Wolff recoil spring.
- bottom of toggle is not rounded and holdopen latch is sharp and not worn.

Anything else to look for? Your thoughts? Thanks, Pappy