I need to remove the head on my Black and Decker GH400. I want to replace it with another type head. I've lost my manual and can't see how to remove the old one.

Request the assembly diagram from Black&Decker.

user manual for my Black and Decker GH400 Type 5 Trimmer/Edger
Black and Decker link to manuals

Which type of the Black & Decker Edge Hog do you have? (This will be on the plaque with model and serial number.)

Black and Decker has the manuals for type 1 through type 5 on their site: http://www.blackanddecker.com/outdoor/LE750.aspx . Click on the Instruction Manuals link.
The direct link for the manual for type 1-3 LE750 Edge Hog is http://servicenet.blackanddecker.com/documents/English/Instruction%20Manual/243420-02,LE750.pdf .

I hope this helps.

Cindy Wells

They have upgraded the old string heads (type 1) to a new string head (type 2). They say type 1 is no longer available. Please see part numbers 20 & 21 in this 14" Grass Hog parts breakdown diagram. The new string head is relatively inexpensive. If you don't want to get one, could I suggest you take the old spring (if you have it) and match it up with possibly a new spring at the hardware store. Sometimes you get lucky! Here is the parts diagram for it. Hope this helps!
http://www.ereplacementparts.com/black-and-decker-gh1000-type-grass-hog-trimmeredger-parts-c-4167_9518_9532.html

The diameter of the Black&Decker GH400 edge guide is 1/8". I know because I have the same problem and a small piece left from the original. Trying to find a new one is quite the quest.

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.

You need to replace the auto feed lever, It is plastic and I have had to replace mine several times. The part number is 385017- 01 G11. Go on line and find a service center such as Dewalt in your area. Lowes, etc. doesn't usually keep them in stock. Hope this helps.

Yevonne

You will need to buy a new feeder head, if your model's head unscrews, normaly when these stop working there is not much you can do to fix it.

http://www.dewaltservicenet.com/Products/DocumentViewPDF.aspx?productid=7997&typeId=4491&documentId=1660


look at bottom of the last page. For for webb address

turn it over it must be in backward