I might be guessing , but are you based out of OZ...???
HG temps *F is always a clue !
By what youre saying here , your HG might not be powerful enough , OR close enough to the bean mass ,and you dont seem to have any way of measuring your temps.
So definitely get closer and fabricate a lid of some sort , be it timber or metal and cover 2/3rds of the BM basket.
Did you get smoke and chaff from your roast ???
Im guessing the whole sheebang didnt enough heat.
If you really have to use the pulsing cycle, you might want to just use the last 3 min of it with HG on low and mounted about 4-6" above the BM basket...... When continuious mixing starts crank up the HG and have the tip at least 1" into the basket , with your cover in place .
Everything becomes easier when you have a thermometer telling what temp the bean mass is .