re: Best trick for bringing in hung up birds

When they are hened up early in the season, fighting purs will bring them in. It's a bit like rattling for deer. You are simulating a fight. I've had a hung up tom lead his hens in looking for this fight after not budging for over an hour.
Get quiet. He'll be curious if the hen is still there and might come.
If it is safe, make hen talk, then cut it off with a gobble tube. He thinks she already has company and will have to cut in.
Be patient. As the season wears on, the hens will go sit on their nest. Mid morning will find the tom looking for company.
Use a slate that you can get real soft with.