The mechanism is the same in the Pico and the Alpha. It sounds to me like you may have experienced corrosion in the pipe, which has blocked the air space between the outer aluminium tube and inner tygon tube that carries the bypass air. That space carries the static pressure from the two mouth cavity pressure sensing ports on the mouthpiece, which is where the breath sensor gets it's signal, so if it's blocked then it cannot function. If you cannot blow some air through it when it is detached from the instrument this does mean that it is blocked - in normal use there is little to no airlflow through this path but detached it should flow, albeit slowly.
The outer tube is made of aluminium (for reasons of weight), which when raw is prone to corrosion. We coat this with a layer of epoxy (the same epoxy used to coat the inside of aluminium drinks cans in fact) and bake it in an oven to cure it. We have seen one failure so far of this tube, oddly just last week - Geert Bevin's died just before he was about to do a large performance and we had to emergency ship him a loaner breath pipe, my one in fact. I think it's possible that the epoxy might fail eventually for some people as the corrosive power of saliva has to be seen to be believed and does also differ from person to person substantially. Geert is of the opinion that his is particularly capable of melting metal and I am inclined to agree with him given that he has what looks like the first field failure of the epoxy.
There are several solutions to this. In the short term if you ship your breath pipe back ti us we can attempt to clean and refurbish it. There would be no charge for this, although we cannot guarantee that it's possible to repair it but we will give it our best shot. In the slightly longer term we have a new, mk 2 breathpipe coming out which uses a completely different inner coating, electroless plated nickel. This coating is much thinner and as a result allows for a more generous air path, resulting in much improved transient response. Given the corrosion issues that seem to be emerging in the long term with the epoxy coating, it is also to be hoped that it has a better lifetime. We tested a version of this with Geert, who played it every day for quite a few months, we then sectioned it and it was in excellent condition. We also had one tested using the standard industrial corrosion test which uses a fog of warm sulphuric acid, and it passed this with flying colours. However, I am now well aware of the astonishing abilities of human saliva to eat metals, so I have to say that we cannot really know until some years have passed whether or not it is a true final solution.
Wayne estimates that the new breathpipes should be available for sale in a few weeks at most, they've been in the process now for over six months and should return from final plating soon. In the meantime, send us your current pipe and we'll see what we can do.
John
UK
