Hi wassie, welcome to Outdoorking.
I am under the impression that all Ryobi Hornets have the usual Ryobi half-crank engine. To me, all half crank engines are garbage, and Ryobi ones at least as much so as others. I would not pick one up out of the gutter if it were in perfect working condition. There are plenty of good full-crank line trimmers available for very little money second-hand, so I do not understand your interest in a half-crank one. (I recently bought a nearly new 25 cc full crank one on ebay for $1, fixed it in 90 minutes without replacing anything, and it works better than any trimmer I've used up to now. Aldi used to sell them for $70 new.) However that is your business of course.
Where fuel lines pass through the outside of fuel tanks, they have imitation rubber or plastic grommets to seal against fuel leakage. The grommets are available as generic parts, on ebay or from a dealer. Just measure the size of the hole in the tank to ensure you get the correct grommet. The priming bulbs are also readily available - there seem to be 2 standard sizes, with the 19 mm size fitting the small machines such as yours, but measure the mounting to be sure before you buy one, or just buy one that is sold for the small Ryobi machines. Generic cutter guards are available for bent shaft machines, but they cost far more than a decent second-hand machine, so it seems more practical to get one from a tip shop for about $5 with a line trimmer thrown in for nothing.
