Obviously different schools of thought on the pstat repair. A new mater or CEME pstat would likely do just fine....the mater has a real nice close deadband and will fit in the machine. The original pstat has such a hefty brass look to it that it is hard to resist repairing it. Lots of different rubber to try if one has the patience...reinforced and otherwise, and I don't think it defaults to overpressure but underpressure so it is not dangerous but aggravating to redo it over and over until one gets the right combination of rigidity and elasticity. But again, upgrading (?) may be the least aggravating way to go. The fact that the membrane in the body of the old pstat was originally a sourceable part from the manufacturer indicates the intent that this thing last a long time with very few moving parts and one wearable part and one wearable switch.
As an aside and part of the argument, I personally REALLY like the old style Olympia pstat....some of these are at top function after what, 25 years of service. The big counter spring on these gets weak eventually and little mods can be done to keep them adjustable within a good working range with about a .2 bar deadband. A MATER, notorious for sometimes lasting a couple of years more or less, is a kindof disposable part with a .1 deadband generally. I like the .2 or even larger deadband as one can pull on the upside or the downside and use the range for some actual temp management and in some ways an even wider range could be desirable for some people, even if just for experiments and observations. So there are arguments each way on old parts vs new parts.

orphanespresso wrote:I don't think it defaults to overpressure but underpressure so it is not dangerous but aggravating to redo it over and over until one gets the right combination of rigidity and elasticity.

Mine was going over pressure as it aged out. Perhaps it stiffened with heat? (It's also possible the friction fit loosened between the pstat and micro switch holder). A pity because you are right, these old pstats are built like a tank. I guess I'm not a patient person in this regards as I only tried out a couple of different materials so far.

Mark

I am also a person who likes to repair the old and generally better made equipment that comes with an old machine. The pressurestat on my newest elektra is also one of the old ones. The membrane is quite stiff and worked for a while and then did not work. Which lead me to question the safety of the machine in a thread in the knockbox ( Safety for the espresso tinkerer ).

But I see that some people have experimented with other membranes. Is there any membrane that someone has found that works best. As far as the deadband goes I am with orphanespresso in his thinking that a wider deadband gives more variables for the user to play with.

I had seen the p-stat thread on your attempt to rebuild. I actually was glad to see the old style stat. I'm with Doug on the Cremina P-stat for all the reasons he gave. There must be something that will work for this one.
There were a few leaks when I fired it up so shut down and now it's completely apart and mostly cleaned.
There was some scale heading into the p-stat so I took it apart and there was some scale inside. The diaphragm looked decent but is most likely a little stiffer than it was. I'll try it out but would like to be ready as it's life may be limited. Doug, got some pieces for me to try? The spring looked fine.
Don't think the machine was used much. The element and inside the tank were pretty nice. Inside the group was fine(gaskets have turned to stone) and the spring looks like new. Everything is cleaning up but the base has just enough pitting so I'm still thinking what I want to do with it.
Are there any concerns with the boiler cap? Or anything else? It seems pretty straight forward.
Ed
The diaphragm on mine is plastic like with no fabric.

Same here on that plastic looking diaphragm. Our original was a kindof plastic over mesh and was hardened and thus had split on the edge. There must be an ideal substance to replace it with. The different rubbers are rated at both duro (hardness) and elasticity. the duro scale I believe is an age old measurement made with a kind of test machine that puts a small dimple in the material and measures how much force required to push through, and the elasticity is the amount of actual stretch before the material breaks. So we have a bunch of different thicknesses and hardnesses on the way, but nothing that is as rigid as the plastic original. I don't know wjat that high temp plastic it could be...perhaps even eisenglass, which would be about right but it could be soluble in water if it is real marine derived eisenglass. Almost seems a try to use the thinnest viton with a support of fine mesh stainless or brass screen (head shop item???). Are they still called head shops or have we moved on to some newer hip terminology?
It would be perfect to come up with some way to test it out of the machine since all you have to hear is the click of the switch....maybe even an air line if you can rig it up. Wait a second, that's MY job!!!!

Well it's mostly finished and is working. Here is a not so good indoor flash picture of it.

Looks superb! Hows the espresso?

Pulled some shots today. The roast was only 48hrs old(a SO Panama DP). The shots are nicely sweet, clean but thinner with less crema than with the Cremina. Doing some research here it seems to generally be the case. Need to play around with the 2 pull technique. What fraction of an ounce on the first up before pulling down and releasing again(was using a double basket).

orphanespresso wrote: Are they still called head shops or have we moved on to some newer hip terminology?

Yep. Still called head shops.