Bests & Worsts Reviews from Amazon

I gave this to my 10-year-old son as a gift for Christmas. We tumbled one one-pound batch of rocks, which was included. It took about a month. It was a lot of fun, very easy, and turned out well as you can see from my picture. My son really enjoyed the process and to be honest I did too! So I bought another batch of rocks and we started a second batch. After the first week, we changed the grit and put the barrel back on the tumbler. After about a day it stopped and all the lights were blinking. Every time I restarted it, it stopped immediately. I looked in the manual for troubleshooting and it said it could get overloaded and react this way. Except since this was the second week, the tumbler was only half full. A lot of bulk is lost in that first week of tumbling with coarse grit. So that wasn't the problem. We got the tumbler to go without the barrel on it, and were able to place the barrel and it kept spinning, but it stopped again within 24 hours, all lights blinking. It just won't work anymore. I'm going to try oiling the pins that the barrel rests on where they join the housing, but I don't know what else I can do to resurrect this thing. It looks as though I spent seventy dollars for a one-time-use-only gadget which is a little ridiculous. Considering this is an educational toy, was quite expensive, and carries National Geographic's name, I would *think* that something as simple as a rubber barrel being turned by a simple motor would just WORK for while. I hate the fact that this device is likely going to the landfill AND the fact that I now have 5 pounds of UNPOLISHED ROUGH ROCKS. I either buy another brand of device and try again--ANOTHER HUNDRED BUCKS MINIMUM--or disappoint my son. I certainly read the reviews before buying this and now I'm left wondering if all the other reviewers only tumbled one pound of rocks and then put the tumbler in a closet to gather dust. Because if their tumblers are like mine, they would never have managed a second one anyway.