Everyone is pretty much all over this being a mechanical issue and they are most likely right because it happens a fair amount. I have had a lot of luck using a spring hook taped to a long screw driver so I can reach back and yank the white clip back into place (typically it is in the "closed" position with the bottle out and won't let the bottle go all the way in).

Another issue I have had at least twice is carefully look at the contacts where the bottle chip matches up. The "spring" wires are typically ok (maybe dirty, but easy enough to clean), but the two connection points on the post, I have had issues with. In both cases, one of the wire connection points was pushed down off the post. You cant really fix that and the sensor board has to be replaced unfortunately. (Not fun to replace, but then anything to do with hoppers and such on this machine isn't fun anyway).

As far as the comments about tech support saying replace the NVRAM, I really wish tech support would train their people better. NVRAM seems to be some boogie man item to say as a last act of desperation to fix something. It is extremely rare that NVRAM is actually the issue and a lot of times there are other symptoms (like going into service mode and seeing data scrambled, etc). I talked to an engineer one time about NVRAM and he told me it is extremely rare it is an issue.