Hi guys, I'm new to this site I have been having issues with my trailblazer LS 4.2 starter. It only has 70,580 miles me and my wife where at the store and when we tried to leave the truck didn't turn on, no crank nothing. Guages turned on had electrical power but it wouldn't crank my lights didn't dim when trying to crank. I had a mechanic come change it out the starter for me did a test on the old one and it wouldn't crank over like the new one. So we installed it ran good for three weeks and again out of nowhere gave out so we replaced it again and now my truck is running good but can't figure out why the starter gave out and worried this one will as well any ideas what it could be?