I haven't successfully made chocolate from cocoa beans, but why do you have to get it to 80 degrees?
http://chocolatealchemy.com/illustrated-tempering/ has a great illustrated tutorial on tempering without seed and they suggest taking the chocolate to 80 degrees to get more types of cocoa crystals then bringing the temperature back up to melt the type I - IV crystals.
However, if you chocolate will only go down to 84, then what is wrong with letting it run there for awhile to build some lower class crystals & bringing it back up to 89?
As far as the chocolate not getting any colder, what is the temperature of your room?
Do the lights come on when the machine is trying to cool to 80? If they do, then that is a machine problem and may be solved by calling Hilliard.
We have a little dipper and it's simple but fantastic.
I cannot imagine the machine would distinguish the difference between percentage cacao chocolates.
The Little Dipper is a seed machine - you shouldn't have to go to 80F to form stable crystals. Remove any crystal memory by pre-heating the chocolate and then start to seed as the chocolate approaches 91 (or so) on the cool down.