Brand new MS661c-m bar nuts loosen and throw chain

[nraws]

Bought a brand new 661 off the shelf the other day and the first time using it, it was fine for an hour or so. Then I barely touched it to a tree and it threw the chain, bent the teeth that go into the bar. I noticed the IRS were loose afterwards. Went back to the shop and they gave me a free chain, next time out it did it again immediately and again the hits were loose. I put a strip of thread tape on them and it fired it up. It held fine for awhile then I noticed them turning again. I realize I could cake the tape on, but the thing is, I shouldn't have to you know? Also who knows it could eventually loosen up while I'm not thinking about it and I don't really want a 32" chain on a 661 whipping in my face.

I guess my questions are, has anyone else experienced this? Or do you know what could be wrong? I'm assuming the threads are just jacked or something. It's under warranty so I can just take it back anytime but I Figured I'd post something about it and maybe learn something haha.

 

[sjwrappel]

Any signs that the bar nut studs are pulling out of the body of the saw? Had that happen on an old saw that I foolishly loaned to my gorilla of a brother. He tightened up the bar nuts so much the studs started to pull out. Just enough to loosen the studs grip in the body of the saw. That was a ****** plastic poulan though...

 

[benjo75]

Shouldn't be doing that. Make sure there's not oil on the studs. You can use a tiny bit of blue Locktite. I mean a tiny bit. You could etch some lines in the backside of the nuts or take some vice grips and booger up the threads a little. None of those I would recommend though. They will work but they're not fixes. I'd take it back and see what they say where you bought it.

 

[Hoowasat]

I once got a good deal on a new MS150 because the bar couldn't be tightened. Closer examination revealed the stud had never been fully seated by Stihl. Using a couple nuts jammed together, I turned the stud home and it's been fine ever since. Are your studs fully seated?

 

[sb47]

I'd be asking for a new saw or a refund. Bar nuts should never vibrate loose.
Could be the bolts were not threaded properly when manufactured.
In any case, I'd be requesting a new saw or refund.