one thing to remember every set up is different so just because some person says do it this way doesn't mean it will work for you, you have to go about a trial and error for a few brews, and yes like above you have to base your recirculation speed on the grain bill and your false bottom, some grains are just plain sticky and will get stuck every time, for those I use rice hulls and it works great, also you want to keep the wort above the grain bed by at least 2 inches for best saturation
issues but not very common that need to be looked at are grain blocking the path and all of the water collects on top then the grain is dry and gets scorched, so its best to have a site glass for seeing where the liquid level is and changing the speed based on that level
the grain is channeling your wort through it instead of saturating and you get a poor efficiency, simple fix stop the heat and stop the pump and stir stir and stir
you should always have a ball valve on the out of the kettle and on the out side of the pump and I have one on the in hose to my mash just for reverse siphoning which can happen when you turn everything off
many things to learn to get it right, most are from stupid mistakes thinking its automatic but no you have to watch it and learn what not to do for a while, I'm to the point where i can leave and not worry about it but I'm very experienced and nobody should really mimic me right off the bat
here's an old set up I had years ago but it shows the valves and the site glass, I just looped it over the top then, I don't now