Craftsman WeedWacker model 4cyc 30CC 17" straight

Purchased April 2023. Have issues from day 1 of it shutting down and hard to stay running once started ONLY after it gets to about 1/2 a tank gas.   On first cold start, starts quick after following the starting sequence suggested. After it stops at a half tank, restart is difficult and if restarts, shuts down within a minute. I haven't looked at the intake syphon inside the tank to see if it floats around properly, but will say the cap gives a strong vacuum sound when unscrewed.   It starts fine when I fill it to full and try again, and then shuts down at a half tank. I'm assuming the siphon filter might not be wiggling about properly, but holding it level on a restart doesn't help either. . . or an air issue with the cap (creating a vacuum as it gets down to 1/2 tank) - I've lossened the cap and screwed back on with no good luck without putting more gas in. Frankly, it could be a heating problem, so I don't know on a new clean machine. Air filter is clean. I've used it about 15 hours so far. 

There's a 2-year warrantee but I've been doing the warrantee phone call blues boogie with the 6th agent so far at Craftsman/MTD/Dewalt and The Garden (?) and three local 20-mile radius "diagnostic service centers" which all three don't work on hand held gas machines when I called so I'm still back at square one with Craftsman. 

Anyone running into similar issues?  Maybe I can just bypass warrantee and find a quick fix (or a recall). Otherwise, I just use it for half a tank before having to fill again and keep looking for an authorized service center.