my best and most reliable whipper snippers are...

Pope 33cc old but very reliable and powerfull , even for cutter blade.
Gardenline, 25 cc old faithfull, i thrashed this little one.... gave it away
Tanaka Japanese 25cc reliable powerfull light...
Makita 25cc 4 stroke.... reliable and powerfull.
Makita 25cc 2 stroke reliable , still using it....

But with all of them, i think the high revs and vibration makes things loosen and go out of tune .
I've got 5 to be looked at......... in the waiting room, and many went to scrap metal.........

cheers
speedy

........................Keep your blades sharp......................