I have an old Starbucks Barista Athena Espresso maker. It has worked like a charm until last night. Everything works correctly until I start to brew the espresso. The green light is on and the green light on the brew switch blinks. Here's the problem--all I get is a hum-m-m and nothing comes through. HELP!!!

I just had my Barista Athena do the same thing. My son took the the coffee basket holder apart, nothing wrong there but the gasket on the bottom inside of the holder, where the coffee basket fits, is compressed letting the basket sit too close to the bottom of the holder. He tested this by raising in the basket and got coffee to flow ever so slightly. I just happened to be looking for a new gasket and saw your post.
It is my understanding that Starbucks is no longer making coffee machines. Your best bet is to contact Starbucks and ask who they may be recommending for repair support.
I hope this helps.