Just a few comments... Regarding flow, I HAVE restricted my flow. At any rater other than shut off I get the 'screaming cat' and the flow shuts down. So ANY flow seems to cause the problem. Even without the screaming cat, the pump is struggling to get H20 from my boil kettle to HLT, which is only a 5' rise.
Second, I did some experimenting this weekend and put some keg lube on the shaft and reassembled. It didn't get rid of the problem but it did seem to allow more flow and temperature before it locked up. This makes me wonder if drilling the impeller would solve the problem.
The comments about the impeller being demagnetized above 200* are a bit disconcerting, as that is precisely where I plan to use the pump! I hope this isn't the case.
Plove, you couldn't pull the trigger if you wanted to as the last batch is already sold out!
Lastly, problems aside you have to give it to chugger that they are standing behind these. I have a new pump on the way already. If it doesn't solve my problem I'll return the pump and I have no doubt that chugger will give me a refund. Their customer service seems to be second to none. I just wish the pumps had the bugs worked out!