Background, I am an engineer who has rebuilt a few espresso machines already, but they have all been rotary machines. So this isn't my first rodeo, but I am far from an expert on these things, so I come here asking for help

Question: The new machine that I have (ID thread here) Who can ID this single group commercial machine? looks to be in perfect condition. There was a mild amount of build up of coffee oils on the screen, but not even warrant replacing it. The guy said that he would be surprised if it was used more than 10 times to pull 20 shots. It is an Astoria CMA with a vibe pump. The entire group head is completely clean, like bare brass, no build up at all. When I plugged the machine in the first time after going all the way through it everything seemed to work (boiler auto fill worked, started to warm up, hot water tap worked, etc). Then I tried the group and nada. So I tore it all apart and followed where I had water pressure. It seemed at the time that the problem was the solenoid. Then it occurred to me to test and see if I had water there b/c if I didn't it should be dumping straight to the drain if it was the solenoid and it wasn't. Sure enough, no water really getting to the three way valve. So I started working backwards, knowing the passageway was clear. As soon as I started to unscrew the glucier, water poured out the solenoid supply hole. I previously checked the glucier to be sure it was clear, and it is. If I reinstall the machine w/o the glucier I get flow, but with it, nothing. I am guessing this means the vibe pump is bad, but don't have any experience with that.

Any tips on figuring that out? How to test it? Adjust it?

The inline OPV isn't dumping water into the trip tray either. fyi.

How are you feeding this machine... is it drawing from a tank or plumbed in? Did you prime the pump? Vibe pumps are not able to pull air well enough to prime themselves.

I am feeding it from a tank. The evidence of the hot water tap working told me the pump was working and it wasn't a priming issue. With a little help from forum member Eric S, i figured out it was a suction valve that was sticking. A little rap with a wrench and she started working immediately. The problem actually only presented when there was back pressure (the flow restricting glucier) and when I removed it, the flow worked well (600ml/min) but installed it would stop pumping.

Thanks for your advice.

Karl