Peel grapefruit using a sharp knife. Slice the bitter white pith from the peel, leaving just a thin layer on the peel. Discard the pith. Cut the peel into thin (1/8 inches thick) slices and place in a medium bowl. (I found this easiest do do by cutting the peel in about 8 sections - I could then flatten it out and remove most of the white pith with my knife).
Cut the grapefruit into sections, removing the membrane and seeds. Add the sections and any juice to the bowl. Stir in sugar. Cover and refrigerate for 24 hours - this is to tenderize the peel.
Stir the orgeat and pectin into the bowl. Transfer to the bread pan fitted with the kneading paddle. Select the jam cycle and start.
Scrape down the sides 5 and 10 minutes into the cycle.
Transfer the marmalade to clean jars. Let cool, then cover and refrigerate. Keeps refrigerated for 4 to 6 weeks.
Note1: Orgeat syrup is an almond-flavored syrup. It is used in cocktails or to flavor coffees.
Note2: This makes a tart, English-style marmalade. For a sweeter marmalade, increase the sugar to 2 cups and the orgeat to 1/3 cup.