It's a RT112C. I don't recommend this model, by the way, for
several reasons. Anyway...
Apparently it's designed to spin very fast. You would think that's
good, but it's not. It causes the line to break off very
frequently, almost as soon as the spinning line touches anything,
so you end up spending most of your time feeding out line.
So what I've done is power the thing through a 3-amp variac, or
auto-transformer, which allows me to adjust the AC voltage level
the Weed Eater sees. This works fine, and I can now set the speed
so that it cuts well but doesn't break off very often.
But this arrangement is a bit cumbersome - I have to set it up in
the front, then move it all to the back - and I'd like to figure
out a simpler solution. Well, I guess I can put a resistor in
series, but I don't know what value or rating. Or maybe a coil?
Well, I just thought maybe someone else had solved this problem and
could give me a suggestion.