OK this of course my opinion of what I have encounter with this model trimmer, so take it for what it worth??

Most identifiable would be spark plug is located at the bottom instead usual models with piston pointing up and spark plug on the top. When I encounter this model the first thing I do is remove the plug and look down the hole for signs of something (needle bearing) banging indentations in the top of the piston. If is see this I know it junk right off the bat. After continue use if it will still run the crank will seperate from the piston making the rope easy to pull and clanking sound. This usually can be verified by watching the piston cause it don't move.

IMO buyers should be aware? seen several of these that crank needle bearing come out and with spark plug on bottom guess where the needle bearing goes? Some may fall out the muffler or when you remove the plug if you are alert enough to see it.

First sign is funny clanking sound, hard to start or no start, which the needle destorys the jug and piston. This style trimmer IMO is too heavy awkard to use and has design flawed needle bearings and with piston pointing downward.

Maybe it will fail before it breaks you back down??? Either way your going to pay IMO.