timo888 wrote:My experience with spring-type dispersion screens is not extensive, though I have never damaged a dispersion screen by using the piston to force it off. The damage to these screens that I have seen documented here on H-B occurred when attempts were made to pry them off. Prying can bend or break the claspers.

Regards
Timo

I agree. It's difficult to find a suitable tool to remove the screen without damage. I tried a variety of things including a crotchet hook but eventually gave up the attempt. My experience differs slightly from Timo's, in that, having clamped under the screen, I merely had to unscrew the clamp to release the spring pressure and the screen came free as the piston pushed against it.

Bob

mousetail wrote:having clamped under the screen, I merely had to unscrew the clamp to release the spring pressure and the screen came free as the piston pushed against it.

Sorry to be so obtuse, but do you actually place the clamp on the screen? Does the piston then not slam down to the screen once released? I'm not following where exactly you clamp the bottom of the clamp, and how the spring tension is gradually released without prior removal of the screen.

Mark

mousetail wrote:I agree. It's difficult to find a suitable tool to remove the screen without damage. I tried a variety of things including a crotchet hook but eventually gave up the attempt. My experience differs slightly from Timo's, in that, having clamped under the screen, I merely had to unscrew the clamp to release the spring pressure and the screen came free as the piston pushed against it.

This was the first time the dispersion screen had been removed from the machine I have. That might explain the relative ease with which your machine's screen was detached.

Regards
Timo

Dogshot wrote:Sorry to be so obtuse, but do you actually place the clamp on the screen?

Yes, I clamped from the screen to the top of the group. The piston in its rest position is almost touching the inside of the screen, and removing the lever pin just caused the piston to settle a fraction of a millimetre down on to the screen. Then I slowly unscrewed the clamp until the residual spring pressure was released.

Bob

Evry time I read a post by you I smile-Great avatar Mousetail / Bob!

mousetail wrote:Yes, I clamped from the screen to the top of the group. The piston in its rest position is almost touching the inside of the screen, and removing the lever pin just caused the piston to settle a fraction of a millimetre down on to the screen. Then I slowly unscrewed the clamp until the residual spring pressure was released.

Bob

I see. Thanks Bob & Timo - I don't yet need to re-lube, but I now know exactly what I need and how to do it when the time comes. Much appreciated.

Lever machines are great - the general design is so elegant.

Mark

I've used a paint can opener to pull off my dispersion screen. This, and a drop of olive oil on the lever workings occasionally, is the only maintenance I've needed to do in 1.5 years of very active service. I always use filtered Juneau water, which is naturally completely soft, and there is PLENTY of it.

I've never noticed any issues with the piston seals getting sticky - perhaps this is because I never activate the lever when the machine is not up to pressure (so water can lubricate the piston). I was VERY clearly told this by Joe at Good Coffee Company the first time I visited there. I grabbed the handle of his brown Sama Export demo machine and was about to test it....

PC

peacecup wrote:I've never noticed any issues with the piston seals getting sticky - perhaps this is because I never activate the lever when the machine is not up to pressure (so water can lubricate the piston).

Never pulling on the lever except with the express purpose of creating coffee appeals to my Christian upbringing , so I have never done that either. I hear that pulling on the lever without creative purpose can also make you go blind . Seriously, your advice makes sense, and I believe that I read this suggestion in one of your posts to getting my Export.

I have not used olive oil yet, but the lever on my machine still feels the same as when new.

Mark

Dogshot wrote:One thing that I like about the PV group that is different from other groups like the Cremina, Pavoni (I think), and also some other spring groups like the Micro Casa is that there is no water exchange between the area above the piston and the area below it. This means that the spring in the PV group never actually comes in contact with brew water (and contacts less lube, seals etc).

Right, there is no water above the piston head. I forgot to mention that the Lusso's piston is not a solid chunk of brass, but a thick-walled (5mm? I forgot to measure) hollow cylinder with base but no top.

Regards
Timo

peacecup wrote:I've never noticed any issues with the piston seals getting sticky - perhaps this is because I never activate the lever when the machine is not up to pressure (so water can lubricate the piston).

And probably because you have not used a strong descaler. I hadn't raised the lever when the machine was cold either. The binding of the seals happened after using Durgol. But the Lusso is back to normal with a little Dow 111.

Regards
Timo