Hi. Pls help and sorry for the Danish misspelling sometimes (o;..

I have this problem that the lever handle kind of goes stuck (cannot engage) when ever the machine is getting hot... When cold everything is fine, but as soon as the pressure builds up, something goes wrong inside, and keeps the lever from being able to engage...

Because of this I have replaced all pistons and the internal lever arm...Still same problem??

Any advice is welcome (o;

Your expansion valve is stuck closed. Your machine is building up pressure in the brew circuit far higher than 12Bar, that excessive pressure is holding your brew valve down. You're lucky it isn't blowing your fittings apart, yet. You want to fix or replace and adjust your expansion valve immediately.

I did a quick online search and found the original USA owner's manual for the Vibiemme DS- It looked familiar to me at first then I realized I CREATED IT in 2007 for 1st-Line!!

The pressure relief valve (or expansion valve as it is sometimes called) is HERE on page 39. That valve (which may be in a different place on your model) can get stuck with hard water deposits, debris in the water, or corrosion. Turn off the machine, remove the reservoir if necessary, and unscrew the adjustment screw seen on that page. Inside is a spring and a piston. Remove those parts and inspect and clean as necessary, and check the bore of the valve as well.

Nice User Guide, Thanks for pointing it out, Randy.

Additionally, René, you''ll want to check the brew valve (the uppermost of the three valves in the grouphead) to make sure it hasn't worn on the end that rides the cam. Being forced open repeatedly with too much pressure working against it in addition to the spring pressure could cause it to wear prematurely...

They all wear down after several years of use. Lubricate the end that rides the cam while you have it out.

Thank you very much for the response. I will take it apart, and let you know if it solves the problem (o;