IH 1256 Injector pump issue

I had a leak there the fuel line comes into the pump. I loosened the fuel line fitting that screws into the pump body, it felt kinda
springy and when I got it out totally I saw that there was a screen piece attached to the fitting that I was loosening. This screen
fitting was screwed into the pump body and the line was screwed into the fitting. So I unscrewed the screen fitting from the fuel line and
tried to screw it back into the injector pump. I couldn't get the screen fitting far enough into the pump body to get the threads started
as a spring was fighting me. I monkeyed around for a while and pretty soon all springy action was gone. It was clear to me that something
was wrong. I looked into the pump and saw the spring laying down sideways and a metal plunger looking piece laying in there as well. I
went and got my manual that had a breakdown of the pump and could see what was going on. This spring was supposed to go inside the spring
fitting, then the plunger piece was to go in after the spring. I fished out the spring and plunger, put them into the screen fitting and
went to screw the screen fitting back into the pump. It screwed right in, there was no springy action at all. Is this normal and correct?
It seems like something maybe wrong or another piece missing being that I lost the springy action that was there when I originally turned
it out of the pump. Any help or ideas appreciated. Thanks

Pumps used to use a black rubber plug in the bottom of the pressure regulator that held the piston and spring in place. They do work out over time and lay in the bottom of the end cap. Bet that's what yours has done too. That plug is no longer used, but a small steel sleeve is pressed in to hold the spring and piston in place.