I have the 780 series trimmer, unfortunately, and persuading the string to
feed is a real problem.
The trimmer has had no more than 50 hours of use so far.

I wind the spool carefully keeping both lines parallel and flat on the spool
or over the previous layer. I leave about 6" sticking out of the spool
housing on both sides and it works great for about 5 mins. In that time I
bounce the knob a few times when it's rotating at high speed. When the
cutting gets very slow, I have a look and one of the strings has
disappeared.

The winding information in Ryobi's manual is pathetic and the sketches are
as useful and as a 5 year old's. The information on their website is not
much better but different from the manual.

" Next, when winding the line, keep your finger between the two lines,
keeping one line at the top of the reel, and the other at the bottom. If the
two lines are allowed to cross each other when winding, then it will feed
until it reaches the point where they cross. You should be able to bump out
the entire length of the line if they do not cross. "

Can anyone understand "keeping one line at the top of the reel, and the
other at the bottom"? Possibly this means one string on the spool and the
other on top of it? Can anyone confirm that this works? My trimmer is some
distance away and I can't check this at present.

A search unearthed some scathing comments about Ryobi's trimmers so I might
have a lemon here.

Comments much appreciated.

Sd