Looking for some help to do with the front brake…I went riding a while back and during the middle of the ride I noticed that the clear (peep sight) on the front brake was "loose". It was actually completely sticking up and I had to grab it or it would have fell to the ground.

I have tried to put it back together but it still looses its grip or suction and pops right out when you squeeze the front brake. It still has brake fluid in the reservoir. I guess im trying to see if I need to buy a new lid, rubber gasket and peep sight or if I should just try bleeding the front brakes to see if the air in the reservoir is causing the problem. I guess my thinking is that maybe the pressure/suction sucks the peep sight into place???

Any help would be appreciated!

2010 Polaris Sportsman 800