Here's a quick video on how to adjust a stuck blow reed on a Seydel chromatic.
The chromatic reeds will occasionally start to settle into the slot and excess saliva will even further reduce the air space between the slot, plate, and reed. This will cause the reed to choke and it is probably most common on the blow reeds. This is not the only cause of a reed failure, but it is one cause and it is a somewhat simple fix.
The key is to know that stainless steel reeds will have a strong tendency to return to their original shape so it is always possible you will still have to pull the plate.