The search terms that work best are the model name or part number (entered without spaces or dashes, i.e. bcz2600).
If you are unable to find the manual you can also try using the product pages - each product's page contains a link to the manual.

Your search results may produce several manuals. They will appear in a unique format. The first date on the left (yyyy-mm-dd) is the date the manual was most recently added to the website. The second line of information gives the following: OM (operator's manual), REDMAX (our company), BCZ2600S (product you searched for), 2003-09 (year and month the product was manufactured), 1 (first issue of manual), 0309 (number from manual). After the file you will see the download symbol and then another description beginning with ZOUS, this again gives the model # and the number from the manual.

EXAMPLE: 2009-03-06 OM,REDMAX,BCZ2600S,2003-09,1,0309 ZOUS2009-BCZ2600S-0309.PDF (1492kb)

The 309 at the end is how you can identify your unit. If your unit begins with a 309 that is the manual you will need, however if your unit begins with a 501 then you will need the other manual in the list.