MNate wrote:-if I have the boiler less than full and turn the main switch to 1, the pump starts, fills the boiler to the correct max level and turns off nicely.

That is what should happen.

-manual fill valve is off, drain valve is off, valve coming off the pump is on (though same issue if this is turned off, the pump then runs but doesn't fill the boiler)

Does water then flow out of the group?

-the anti-depression valve does open properly as the machine heats then closes again when I turn the machine off - not sure when it is supposed to turn off)

The anti-depression aka vacuum breaker valve should fall open when the boiler pressure is no higher than atmospheric. So a certain temperature above 212 F it should close and open again when the steam pressure in the boiler falls close to atmospheric.

-the gauges are still wacky... The boiler pressure gauge stays at 0 but presumably because the boiler hasn't heated enough to build pressure (this gauge did work before). The dispensing pressure gauge is way out at crazy and hasn't moved - when the HX was cracked this one was moving crazy because of that.
-the dispensing button, up or down hasn't mattered. The machine doesn't warm up enough to have that or the volumetric buttons light up. (Draining the water after hearing shows the water is at about 150degrees)

I don't think I follow all of this last, however if the boiler turns off before reaching a high enough pressure to open the Sirai pressure stat / switch, then I wonder if there is a wiring misconnect or maybe a problem with the Sirai.

Thanks again, all, for the insight.

I think the 'overfill' aspect has been solved. I've been following Almico's Thread Astoria Argenta SAE-1J on his restoration of a similar machine and found a few screens that were severely clogged. Cleaned them up and now I've got normal workings up to the point of the boiler reaching operating pressure.

My next problem was no water at the group. My group pressure gauge is clearly broken but I wouldn't think that would be the cause. Following this very helpful thread Checking an E61 Espresso Machine for Scale, I've removed the 'mushroom' and cleaned it out twice. The holes appear to be clear... but when I put it back together no water to the group (great steam though) and then when I take that mushroom back off there is water down there. So perhaps I'm still not clear on the clog there or there is another problem between that and the shower screen (which I have taken off and cleaned - it seemed very clean already, much better than my Silvia after a month of use).

More spots to find clogs? Better way to ensure I've really cleaned out that mushroom chamber? Did I do something wrong in replacing the HX...? (before I did that I could get a few drips from the group for about a second before it would get clogged). Or should I just start replacing stuff...(I was kind of hoping to get it working before replacing things to get it working well, just in case I decided to scrap the thing).

Well, thanks again! Someday... someday...

To solve my group water issue I disconnected the lime pressure and had the pump draw out of a bucket. This way I knew that I was only getting flow when the pump was on. Otherwise as soon as you start disconnecting tubing you're going to get a flood.

Start at the pump and disconnect the outlet connector. Turn on the machine and then the manual brew switch to start the pump. Is there water coming directly out of the pump? If no, the issue is with the pump, or before it.

If there is water coming out of the pump, start working your way to the group one connection at a time. My issue was a screen filter just before the flow meter. You might want to disconnect the outlet of the flow meter and see if water comes out of there when the brew switch is on.

If so, the problem is further on. The inlet from the HX to the group goes through a tiny hole about .025" in diameter. See my thread for a pic of it.

Took my time doing this (in part due to lack of time and in part because of intimidation). I removed and cleaned all the front hydraulics as well as the group head. Didn't look too bad but there were several screens and small orifices which could have been clogged. Also replaced the nanometer and the anti-depression valve since it was cheap. Now things seem to be working well!

I still have to get the water connection to stop leaking (finding the right pieces was quite difficult). And I have lots of learning to do on how to use the machine. I've got the cafelat bottomless/mini-double portafilter on its way which will be great because currently it's just a 7g single which also takes some getting used to.

Generally I'd say nothing on this was super tough and if anyone sees another come up cheap it would make a fine rebuild. Yet to find out how well it makes espresso but it has decent specs for an HX. Perhaps I'll post another recap with tips and details and a final pic.