20 Most Recent Black & Decker String Trimmer Cordless 12" 18V - Page 8 Questions & Answers

Sounds like you may have lost the little metal grommet that should surround the hole that the business end of the string comes through. This grommet is usually aluminum because it is a very good heat conductor. What happens is that the string rubs very hard against the edge of this hole, which heats up the string in that one little spot enough to melt it. If the hole is only plastic, it cannot dissipate this heat. The grommet dissipates that heat and the string doesn't melt. I don't know if you can buy a replacement grommet. You might be able to a generic grommet like the kind sold for tarps. Or you can replace the whole part that should have the grommet in it.

Use 50:1 gas/oil with a GOOD QUALITY 2-cycle low-ash synthetic oil.

Remove the muffler and check the spark arrestor isn't partially blocked.

With a clear muffler, and the mix as described, there will be hardly any smoke at all.

The ST6000 uses centrifugal force. Once you mount the new spool of string and thread it out of the feeder and into the housing below, plug it in, give it power and hold the line feed button down, feeding the line. Within seconds, the line will feed out through the head and you'll be in business.

they often bind and a pair of channels locks will give the leverage to unscrew, and grease the bolt to avoid such issues. have a nice day.

It's a screw mandrel for use with some polishing accessories

MANUAL:
http://www.dewaltservicenet.com/servicenet_home.aspx?AspxAutoDetectCookieSupport=1

PARTS:
http://www.ereplacementparts.com/black-and-decker-grass-trimmer-parts-c-4167_9518.html

http://www.dewaltservicenet.com/documents/English/Instruction%20Manual/598012-01,NST2018.pdf

9 hrs before first use. 3-6 hrs thereafter.

MANUAL:
http://www.dewaltservicenet.com/servicenet_home.aspx?AspxAutoDetectCookieSupport=1

PARTS:
http://www.ereplacementparts.com/black-and-decker-grass-trimmer-parts-c-4167_9518.html

Is the spool seated on the rachet properly?

possible stripped plastic reduction gear (just inside bottom of motor housing). Make sure that no grass is bound up between moving and non moving parts. This is a chronic problem and will lock up the unit.