Mamiya 7 repair question

[Maineiac]

The little fold-down tab on the bottom of the camera that raises or lowers the light-blocking curtain when changing lenses split in two. I called Mamiya and they sent me (for $3.00) two replacements along with a schematic that shows that the little tab is held by a spring-loaded pin, similar to that in a watch band. However, try as I may with a tiny jeweler's screw-driver, I cannot depress the spring enough to pop it out. There's not enough space between it and the collar around it to allow even a tiny screwdriver to fit in.

Does anyone else have experience in this small, and seemingly simple repair?

Larry