I am trying to locate the plastic cover that goes in the middle of the black lid. Don't know the correct term for this part but it's the piece the you can take off and pour stuff in to the pitcher as it is running.

The piece is called a "filler-cap"--that round, clear twist in part with teeny 1oz and 2oz markers inside. There is a used one for sale with the lid that may possibly fit your blender on the cheap at http://www.ebay.com/itm/VINTAGE-HAMILTON-BEACH-BLENDER-REPLACEMENT-GLASS-JAR-LID-with-FILLER-CAP-BLACK-/161614461759?pt=LH_DefaultDomain_0&hash=item25a0f8fb3f For an unused replacement, try typing in your model number at HB's parts site, located by clicking here . Many www sites like abtecparts.com and goodmans.net could help you. Besides matching description, I would match the pictures of what you are going for against what you've got as much as possible. Good luck!

The blender we bought called that piece the measuring cup, It has increments measuring liquid by the ounce. I am not trying to over simplify but the manufacturer whether on line or on the phone often they have a replacement parts list. The web is the best place and usually has the list attached to the model.