the clue to "blown diode syndrome" is usually *that the pump vibrates, but wont pump properly when the extra resistance of the puk is added to the group. It kind of looks at first, as if the grinds have choked the flow. So Im surprised the machine was able to brew coffee (in the normal sense) at all! No wonder the coffee now tastes better *:D
Fortunately, blown diodes in this application are not really a common occurence, this being therefore a good example for the CS forum.
Your BZ35E must be an "early/er" model. Theyve had rotary impeller pumps fitted atleast 2 years now that I know of.