ILENGINE,
Learned something that might be useful to you.
I took the XT-7 to a reputable, local, small engine/mower shop. They have seen the same problem. They attribute it to ethanol, which in this neck of the woods is supposed to be 10% of volume, but at some stations is testing at 20% or more. The effect is to corrode metal parts and rot hoses and seals. They keep a show-and-tell demo carb by the cash register. It is corroded.
Their recommended solution: 1) fresh fuel only, nothing older than 30 days; 2) by trial and error, figure out how much fuel it takes to mow the yard and use that amount... if it runs out, add just enough fuel to finish the job; 3) each time, run the engine until it is empty; a couple ounces of SeaFoam added to the last bit of fuel on the last run of the mowing season.
I'll get my XT-7 back in 10 days and will let you know how well the strategy works. Two neighbors (who use the same repair service) swear by it.
Cheers,
Beekeeper