If you're only having this problem on the HR20, I'm betting it's an HR20 problem, not your dish. Other folks have reported this problem, so it could be software. Also, be sure to remove your B-Band Converter modules because some of them are defective and might cause this problem. Personally I would wait until after the next software update.
Not sure where you heard that the Andrews LNB's are "sub-standard". I haven't heard that.
Not sure where you heard that the Andrews LNB's are "sub-standard". I haven't heard that.