1377 pump arm and INPA sight questions

[vintage42]

On my Crosman 1377, two questions:
1
I changed to a steel breech which the original rear sight does not fit, so I got an INPA rear sight.
http://www.amazon.com/Crosman-LPA-Metal-Rear-Sight/dp/B00B3N0DH8
In the middle of the top of the sight, not visible in the photo above, is a large screw that would appear to adjust elevation. This screw feels locked. It has an almost imperceptible wiggle so it's not frozen, but is solidly locked against strong attempts to turn it with large screwdriver in either direction. Is this an elevation adjustment that is supposed to turn?
2
The pump arm has side play or wiggle so that I have to be careful when pumping not to hit the trigger guard. Hitting the trigger guard when pumping sounds and feels bad, and it reduces the pump stroke. I have learned to use the pump so it closes around the trigger guard without hitting it. But is there a way to eliminate the side play allowed by the pin(s) of the linkage of the pump?

[BillK]

1.  It is an elevation adjustment.  Press down on the back of the sight and hold while turning the screw.  That relieves the tension allowing the screw to turn.

2.  I use the bushing & reinforcing ring from Mellon.  Should have a good pump pin also.
      http://mellonair.myfreesites.net/index.php?p=1_12_Solid-Pins

[1377x]

the pump arm can be spread apart that helps with the slop also

[mudduck48]

I fit a washer in between the halves of the pump arm. Works great.

[vintage42]

I fit a washer in between the halves of the pump arm. Works great.

How do you get the pump arm out to spread it and get a washer in? Drive out its pin, I guess. I wonder if to avoid that, a circlip could be used instead of a washer. Make a gap between the halves of the arm by twisting a screwdriver blade, and tap the circlip into the gap onto the pin.

[BillK]

You would be much better off to just buy the pin ect. from Mellon.  There are probably a number of other options but I know this one works.