Everything went according to plan until I got to this bit in the recipe:
"boil until mixture will form a gel about 5 minutes. To determine when the mixture will form a gel, use the spoon test: Dip a cool metal spoon into the hot fruit. Immediately lift it out and away from the steam and turn it horizontally. At the beginning of the cooking process, the liquid will drip off in light, syrupy drops. Try again a minute or two later — the drops will be heavier. The jam is done when the drops are very thick and two run together before falling off the spoon."
Well I was never able to get the jam to reach the point where "the drops are very thick and two run together before falling off the spoon." By the time I had cooked the jam for about 20-25 minutes, I finally said to myself: "okay I've had enough of this nonsense, this jam is done."
So I finished and canned the jam. This morning when I opened a jar, low and behold, the jam was like glue. Shoot. Oh well it still tastes awesome. I just need to add a bit of water to it every time I use it, to thin it out a bit.
The recipe also had a one to one ratio of sugar to berries. That's a crap load of sugar. There are other recipes that use a two to one ration of berries to sugar. That's what I'll use next time.
Today I found this site that gives a more in-depth procedure to check for done-ness. Maybe next time I'll have more luck in figuring out when it's cooked.