How to Make Tumbled Crosses

I'm definitely late to the party on this one, but yeah.. The Dual and Single units use the exact same motor and it's definitely a issue when it comes to 'moving / rolling' rocks around the barrel(s). Also, if the motor starts to weaken, you'll absolutely notice it and this very thing happened to me. The critical thing about these motors is that the Weighted Fans absolutely need to be aligned properly so that the motor does NOT oscillate improperly and stress one side of the arbour. If they are not aligned properly, you'll notice right away that one barrel (in my case, the right barrel) will start to roll the rocks 'slower' than the left side and the machine will become much louder and start to make a slow repeated oscillating noise, usually accompanied by more vibration (vibration that doesn't help) and eventually this will lead the motor going bad.
The other thing is that I've noticed is that the single vibe REALLY rolls those rocks round quickly and consistently and the performance is just so much better with ALL grits, especially lower grit (220). The ticket for me is using a half tablespoon of borax (full tablespoon is too much for my dual) added slowly AFTER I have slowly added a full Teaspoon of 220 grit (1/2 TSP for stage 3 & 4). It seems to really help with not having it 'bung up' all the time. The other thing I noticed about the dual vibe is that the barrels need to be re-charged after 12 - 24 hours no matter what grit or how much you are using, but the single seems to keep on going with the additional few squirts of water which leads me to believe that the motor size HAS to be bigger on the dual vibe if it plans on keeping up with the single barrel unit. The motor on the single vibe unit is more than adequate, but not so much on the Dual...
Cheers,