Hi
I have an '04 Silvia which has never seen the slightest issue whatsoever. Amazing machine. I love it. However last week it started acting up a bit. I use a naked PF with a 3 shot filter so I can follow the flow and also cause it's really cool to see the funnel of crema stream into the cup ) However as of last week I can't seem to get a good flow. It almost seems like there isn't any pressure in the group and the shots come out on the bitter to tasteless side and only about half the volume. So I went and disassembled the pump and cleaned it thoroughly along with giving the whole machine a good descaling and rinse. Nothing, didn't do squat. I have then noticed that even though I'm running water without the PF on there seems to be running a lot of water through the return hose to the tank. So I suspect the OPV (non adjustable) to be failing or stuck. I then disassembled the OPV and got a the innards out and descaled and rinsed them over night. Looked like new. Again, nothing, didly. So I'm guessing the problem is inside the main housing of the OPV, problem is I can't get that thing off. It's stuck. But I assembled everything again and did a backflush where I drew a lot of descale through the OPV and return hose and let it sit over night. Again nothing. Just FYI I haven't backflushed much before as this was not recommended by Rancilio nor my retailer. But before I go and put even more muscle into getting the OPV off, with the risk of breaking something, can anyone tell me that this is actually the issue? Or is it the pump? If it's the pump that's an easy fix. Please help.....

Can you run the pump directly into a pressure gauge?
That would tell you quickly if the pump is busted.
Iirc the opv on the Silvia dumps back into the water tank. Can you monitor its output? If no/low flow from OPV or group, then pump is a problem. If lots of flow from OPV but not group then suspect OPV.

If I'm wrong about the OPV dumping into the tank, is it possible to disconnect it and run it into a cup to watch the flow?

Of course a portafilter pressure gauge would also be of immense benefit.

Hi
So I made my morning latte with the intent of figuring out what's going on. First off I purged the group with a measuring cup under the group and the return hose. Good news. Nothing comes through the return hose, hence not through the OPV, anymore without any pressure on the group. So far so good. As for the water coming through the group I got 300ml in 30 seconds. Is that good or bad? What is the pump rated for? It's the original 48w, 230V Ep5 Ulka I have in there. So on to brewing. I pack a three shot basket and pull a shot still measuring output on the return hose. In 25 seconds I get 2 ounces in both ends. 2 Oz coffee and 2 Oz through the return. If I was just looking at these measurements I wouldn't be worried at all (or am I missing something....am I misinformed some way?), but when I look at the extraction I don't get my beautiful crema funnel and the taste is bland bittery shot....but why?!? Just a few weeks ago I was pulling dreamy 100% crema shots with a 1 inch funnel that tasted like joyous tears of angels.....

Hi
On another note. I can't seem to choke the machine at all. Tried the finest grind on Rocky and I more or less stood on the tamper so it was packed. No dice. No choke....I used to choke it if I wasn't careful with my grind and tamp......what is going on???
Klaus