Since you feel compelled to pull the sight, Here is the low down on pulling just the housing(leave the peep alone).
Start by driving out the roll pin just below the elevation knob. A spring will drop out of the inside of the housing elevation screw {inside of upper receiver).
Then slowly start to turn the elevation knob counter-clock wise. The housing will come up, and at the top, the spring and detent ball will want to pop out. Retain the ball and spring, then finish screwing the housing out. The elevation knob should be left alone, so don't try to pull it out.
Once you have done your build-up, start by slowly screwing the housing back down. Use a little grease, and insert the spring/ball back in the hole and retain the two until the the upper receiver holds the two in place.
Then get about three turns down on the elevation knob, and insert the pressure spring back in the housing elevation screw, threw the bottom of the upper. If you can find someone to help you hold the spring in while you punch the retaining roll pin in, it will save you from having to grow a third hand. The easiest way is to use a small punch, and hold the closest side of the spring to the roll pin to allow the roll pin to get over the top, then drift the roll pin over just short of the other side of the spring,then press down on the loose edge of the spring and drive the roll pin the last of the way.
Note: I have a U-channel tool(punch with a slot for the roll pin to go threw) that allows me to press the complete spring down and drive the roll pin straight threw. Without the tool, just work one side at a time.
Hope this helps.