My trimmer only runs about 5 minutes on a fully charged battery, It seems to be overheating. If I let it cool off it will run again, but only for a short time. sometimes grass gets caught around the spool, I have taken off the spool to remove excess grass. Is there a diagram that describes that disects this part of the unit to show parts and how they go on.

SOURCE: ryobi gas trimmer

I don't mean to over simplify this, but are you using fresh gas? Gas string trimmers are extremely ticky when it comes to gas. They like it SUPER fresh. And while the gas and oil mixture should be right, it can be off a little bit and still run. Try draining all of the gas out, and then filling up with fresh mix. This is ALWAYS my first step with string trimmers, and it fixes the problem 75% of the time.
Hope this helps!!

chad

SOURCE: 725r trimmer

You can buy new Line to re-spool on your existing head

SOURCE: RYOBI CS 26 stopps after 2 minutes

My suggestion is to return it. This is just a sign of future problems you are likely to have in the future. Think about buying a better item from a dealer that services what they sell. It is very much worth the difference in price. More than likely the unit they sell you will last 5 times longer than what you buy in the home center. Think about it. The servicing dealer does not want to have to repair everything they sell 4 or 5 times a year so they will not sell you junk.

SOURCE: my ryobi grass trimmer will only run on 1/2 choke

Check for fuel supply problems (clogged cap vent, dirty tank fuel filter, clogged or faulty fuel intake lines, leaky or cracked primer bulb, air leak in rear crankcase cover...check 4 screws above gas tank, air leak in carb gasket...check carb nuts, trashed up carburetor...needs cleaning or rebuild, mixture screws need adjusting)....a myriad of possibilities here but I would guess it's a dirty carb....hope it helps