Small Engines (Lawn Mowers, etc.): tb string trimmer, commercial landscapers, stihl kombi system

Question
HI Eric,
I have a TB90BC string trimmer...it has the ez link coupler. There seems to be
a problem with the coupler on the engine side of things (I've tried two string
trimmer attachments). The engine runs fine but the trimmer will not run or
runs for a while and then stops. There seems to be some play with the
coupling mechanism. I can push the coupler up the shaft towards where it
couples to the engine and there is about an inch of play. Hope this makes
sense.
Is this an easy fix? I've already put more into this thing than it's worth. If I can
fix it easily I might give it one more chance.  While you're at it, can you
suggest something reliable? I'm tired of buying things that seemed to be
designed to live in the shop.

Answer
I'd check the cluth on the power unit.  You will have to dis-assemble to inspect the clutch.

Stihl are way better quality system and I see a lot of commercial landscapers using the Stihl Kombi system.  They cost more but there must be a reason the commercial folks don't use TB trimmers...reliability.

Eric