A good friend of mine showed me a nifty solution for those pesky detents...
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Drill a 3/32" hole through a 1/4" dowel about 1/4" from the end. Slide the dowel right through the pivot pin holes from the back side and line the hole in the dowel up with the spring/detent hole in the lower. Drop in the spring, drop in the detent, and push them in with a 3/32" punch until you feel the punch contact the lower. Use the punch to rotate the dowel until the detent is blocked in. Leave the dowel in place and remove the punch. Using the pivot pin, line up the channel with the detent, and slowly push out the dowel. When you feel/hear the detent click into place you're done.
Takes a while to type, but only about thirty seconds to actually do it...