Husqvarna trimmer 952-711953 128LD starts but does not stay running

SOURCE: Husqvarna looses power after 10-15 min.

Hello Matt:

From your Description it Sounds like Either the Gas Cap is Not Venting the Tank, the Exhaust Port/Muffler is Restricted or the Rings are Worn Out and Require Replacing.
Make Sure the Gas Cap Allows Air into the Tank.
If the Gas Cap is Good, then
>>The Following is a Basic Instruction File for Doing a Diagnostic on the Engine for this Problem. Any Input is Appreciated.
>>**Remove the Muffler and Make Sure the Exhaust Port is Clear.
>>If it is, then Try to Start the engine with the Muffler Off.
>>If it Starts and Runs Properly, then Clean the Spark Arrestor Screen in the Muffler or Replace the Muffler if Required.
If the Exhaust Port and Muffler are Clear, then Most likely the Rings are Worn and Require Replacing.
Please, Do Not Hesitate, If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance.
Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Be Happy. Thanks.
Good Luck

Respectfully

John

SOURCE: Trimmer won't stay running without starter fluid

drain any old gas/fuel mixture out of unit.
purchase new gas and mix with oil as recommended for your engine.
clean the air filter on the unit.
pull the spark plug and clean with carb spray and reinstall...

you also may need to remove the carb and clean any jets with carb spray... old gas can turn into a shellac'ish type goo and foul up the works...
I recommend draining all fuel after usage...

SOURCE: No Spark - Husqvarna 125R Trimmer

Check the wire that goes to the "OFF" button. See if it is by chance loose or cracked allowing a short. Beyond that, it would probably be the coil, but I would lean towards some type of a short, especially if you know the plug is OK.

SOURCE: After starting a trimmer, Husqvarna 128LDX, motor runs fine, but trimmer head wont rotate with any power , or velocity.

A couple of things here, are you sure the two halves are securely together? if yes you need to check the squares of the drive shafts at both ends, these are flexible drive shafts squared into the gearbox at the bottom, and into the drive drum at the top, if they have rounded off they will slip and stop altogether if the trimmer head is loaded up.