The Andreja now shines just like it did the day I received it...
In addition to the cleaning, I opened the Andreja up again to see if there was something I could do to make it a bit quieter. A vibration pump does make noise and this noise is difficult to dampen. Regardless, I checked the pump mountings and they were ok (the one towards the front of the Andreja is very difficult to access).
However, in addition to the pump noise, the Andreja made (and has made since new) noises that sounded like there were parts resonating against each other or the outer shell of the machine. I added a few pads to prevent the cup warming try from rattling and on the inside it turned out that there were a couple of wires at were hanging a bit loose and this allowed the plastic (insulated) wire-to-wire connectors to make contact and resonate with the frame and/or the shell of the Andreja. I used a couple of cable ties to tie the wires in and keep them in check.
Now this is the part where I come up short in terms of my lingo / jargon, but I hope that the following makes some sense (no pics, sorry). The wire leading to the water reservoir sensor is long - it is attached to the divider (between the reservoir and the machine's internals) and it needs the length if one wants to be able to take the divider off. This leaves a loose wire inside the machine when it is fully assembled and the wire connectors lay against the divider wall causing a resonance. I double folded (didn't want it stick to the connectors) some electrical tape, wrapped this around the connectors a few times and finally used some tape with exposed adhesive surface to hold it in place. The wire could be cut shorter, but then one would have to undo the sensor connection every time prior to taking the divider off - too complicated for me.
Finally, I tweaked the brew pressure coil slightly. It was not sitting tightly against the boiler insulation and it was uncomfortably close to the wall of the internal divider. I placed the coil a bit more on the side, closer to the over-pressure valve and made sure it sits snugly against the boiler insulation.
I put the Andreja back together to see if the above made any difference in the noise levels. Well, the pump is still noisy, which is not a surprise and there still also seems to be some noise caused by resonance - I just can't figure out what could cause it as I went through all the parts and wires inside the Andreja. Having said this, I am still very pleased with the overall result as there is perceivably less noise and almost all of the resonance-type noise is gone. It took some time to do this, but the machine is a bit quieter - and this was the goal after all...