Machine is tuned on. Water level ok . Pressure 1 bar.
After about 4 hours; beeping alarm, pressure drop to .8 bar, no red light, white lite on.
Beeping continues and machine just sits there quite content .
Leaking probe seal fixed and thought to be the problem, but not.
No leaks anywhere in machine detected.
the water alarm coming on will be responsible for all the symptoms you describe, so dont worry about those
reasons the water alarm triggers;
1. water box not fully seated into the water box carrier: push down on both ends of the water box with both hands and see if that turns the alarm off
2. the two brass electrodes beneath the water box are corroded: pull water box out and give the tops of the brass electrodes a polish so they shine again
3. the stainless steel pins in the bottom of the water box have been pushed into the water box too far and as a result they no longer touch the brass electrodes below: remedy; remove water box, empty, push stainless pins back out so they protrude out of the bottom of the water box by about 2mm. the bottom of the water box also tends to concave as it ages and you may need to push the stainless pins out slightly to compensate for this movement
4. the pump is unable to refill the boiler within i think 30 seconds: cause is partially blocked/obstructed inlet solenoid. go to the permanent file and on about page 8 you will find a video detailing how to take the inlet solenoid valve apart and clean it
there are probably some others but one of the three above is probably the most likely
let us know what you discover and we can take it from there