I use the weedeater string also,so as to catch them when they cross a road.I use 30' to 40'.when they come by at full tilt 10' ain't enough.when you do catch her,praise and pet her a bunch.

I have raised beagles for about 40 years now.an old gentelman told me when I got my first,he said when you feed you puppys and even after they are grown,while feeding them pee on the feed and around the pen. it may seem dirty and nasty, but it works.
it gives them your sent and they know they can trust you.

we have 5 or 6 different guys that hunt with us.they all have a problem with a few of there dogs,(catching them).I have only had one dog that was hard to catch,like you said.it was one I got from another guy.after about 6 mo's. she was just like all the rest of my dogs.no problem to catch.

I don't know what it does,but it works.at least it has for me for the last 40 or so years.