Had a interesting experience with my left side cap lock cover a few weeks back when I went to fill it up, could not get the thing to flip up. I didnt want to force it and only needed a gallon to make it home so I just filled the right. Once home I got out my feeler gauges and worked the little ball and got it open. Then it wouldnt shut. This was my method- do what ever trips your trigger or do nothing But I blew out the area with my trust bottle of compressed air for my computer, then put tiny drop of 3 in 1 on each ball and worked it with the .003 feeler gauge. Did both sides right away and have not had a problem since. Im sure someone will say use WD40 or teflon or what ever, BUT- this is what worked for me and I am riding in dusty sandy conditions nearly every day. The 3 in 1 has not collected any grime to the area. I used the tip of a paper clip to apply it, I didnt trust my smooth squeeze of the can to drip one tiny drop: im sure it would have been way too much. Not that this is something to re-write the manual for. But it sure could have been a hassle to deal with if I really needed to fill that side up. Pics show the places where the little balls are. Its just a simple ball (plunger) and detent system.