Here is a quick tip to help get a stuck sparge flowing again.
On my most recent wheat beer brew session, I flipped open the valve at the end of the mash and all I got was a drip drip drip. But I did not panic. A very quick simple blow in the tubing off of my mash valve until I had a good couple bubbles up out of the mash got things flowing again. I must have had a clump of malt or something blocking up the inlet of my SS braid. Or maybe the braid had just crushed or twisted in some weird way right at the inlet. Regardless, after I blew it out everything was running good. I did a gallon recirculation to get things running clear.
If the blowing in the valve end didn’t work, then a gentle stir of the malt would have been my next step. Just get your spoon or mash paddle down near the manifold to try and loosen the malt a bit. Sometimes you can get some unhydrated malt or malt flour making a sort of gummy plug the prevents things from flowing right.
I have found that a good infusion of hot water to get close to mashout temps (168F) really helps to reduce the viscosity of the mash too.
The worst case scenario is that you popped off your manifold. The only solution you have is to get a small sauce pan and start scooping out malt into a couple buckets. Correct and clear the manifold. Then reintroduce the mash to the tun. It seems pretty pain staking, but it works.