On a new black and decker 20 V string trimmer, I put the guard on before I put the battery in, removing guard

SOURCE: BLACK AND DECKER CST 1000

see www.dewaltservicenet.com look for find it now icon then enter the model #

SOURCE: Black and Decker 16 in Hedge Trimmer

I use a dremel with a sharpening stone, if u don't have one you can also use a power drill with a small sanding disk (1 inch) and course sand paper (30 or 40 grit). or you can use a bastard file. its too tight to use any kind of angle guide so just take your time and do it by eye. it shouldn't take much to get them sharp enough to do the job, over-sharpening is unnecessary and dangerous, and will make the blades dull faster. sharpen all the free blades, top and bottom, then start the trimmers to advance the blades to free up the sides you couldn't get. i use a light penetrating oil to clean the blades first, then lithium grease spray to lubricate.

SOURCE: put string on tb425cs troy bilt trimmer

there are two ways to install the string..the cool way is without pulling the inner reel off the trimmer..just leave it in place..cut (2) approx.two arms length (thats spreading your arms out like airplane wings) of .095 string..now, align the arrow of the inner reel (it turns counter clock-wise..the arrow points outward) with the arrow on the outer spool (pointing inward)..holding the spool and reel together so the inner reel doesnt move, push one of the cut strings through the eyehole in the side of the outer spool, and it should come up to the right, through a slot next to a small round hole the diameter of the string..if it doesnt, it just missed the exit (as i call it)..pull out and try again..let about an inch come thru..now take that end of the string and push the line into the little round hole until it stops, which should be about a little more than 1/8 of an inch..hold it in while pulling the excess line outside the spool to keep it in place..now do the same with the other string for the other side..once you have both lines in place, turn the inner reel counter clock-wise to draw in both lines through the eyeholes of the outer spool..you may or may not get all of the line to wind in..not a problem..you will still have enough to do what you need to do..just cut off the rest..one problem you may or may not have that i do most of the tyme is that it gets hard to turn the inner reel..one solution is to bump the top of the 'bump knob' with your fist, then pull both strings at the same tyme, then continue to turn..this method is quicker and easier than the second way of having the inner reel out and trying to wind both lines at the same tyme and trying to place the reel back in the spool..hope this works for you...

SOURCE: Black & Decker 8209 Weed Trimmer

I went to the B&D web site and downloaded the manual for this unit.
Here is the link

http://www.blackanddeckerservicenet.com/Products/ProductManual.aspx?q=8209

SOURCE: B & D auto feed string trimmer won't advance string

Is the string spool seated on the rachet correctly? If so and all is well, it is worth noting that these trimmers auto feed fuunction is problematic at best, requiring manually unwinding some line every few minutes as the unit gets older.