I camped at Mine Shaft Flats last weekend and Mine Shaft Spring is flowing strong. You take the Big Tree Camp trail (North Fork Meadows) out of Mine Shaft Flats camp. Follow it for about 0.4 miles. You have to descend the slope off trail for 100 yards or so before you get to the spring. The coordinates to get off the trail are 34.10397, -116.80894. At least that’s what my device recorded. Interesting note, if you see a rotor from a helicopter wreckage, you are in the right spot.
This is also a link to my recorded track on Gaia GPS: https://www.gaiagps.com/map/?loc=17.4/-116.8097/34.1076&pubLink=DcUe2B5t1U4yIwZSNut5CSJM&trackId=229f24f92769f8c56137a5ae69e19a3b
Hope that is useful.