Chris,
Unfortunately no further suggestions can be made concerning this issue so far as user performed trouble shooting. At this point the next course of action would be to take the unit to a servicing dealer for potential warranty consideration, be sure to take the unit with the POP to one of the dealers near you by utilizing the link provided below:
/images/us/homeowner/dealers/dealer-locator/
I just bought a 128LD from Lowes with this same problem. Lower shaft will not fully engage. Turned cable from power head to no avail. My answer is to return it to Lowes and let them deal with it. If enough people return these maybe Husqvarna will improve their quality. In the factory I work at this is called an OBF (out of box failure). My customers don't accept it and neither will I. I'm going to take it back and buy a Stihl.
I ran into this issue with my trimmer today when attempting to assemble and fire up for the season. When attempting to connect the head to the base, I could insert it in such a way that the internal cables would connect, but the shaft itself would not slide all the way down to lock in place. It kept sounding like it was hitting something firm and it just wouldn't give. I managed to fix the issue so let me explain what I did:
Note that I am by no means a repairman or savvy on these things so please excuse my terminology for some of the pieces.
Hope this helps!
Chris,
Unfortunately no further suggestions can be made concerning this issue so far as user performed trouble shooting. At this point the next course of action would be to take the unit to a servicing dealer for potential warranty consideration, be sure to take the unit with the POP to one of the dealers near you by utilizing the link provided below:
/images/us/homeowner/dealers/dealer-locator/