Krups PIXIE Coffee Machine Red Led Issues

Hello everyone, this post is oriented to all of you who love a good cup of coffee, made using the Nespresso method.
As a coffee-loving Italian, I must say the quality of the coffee pouring from these machine is indeed really high.

I received as a Christmas present one of these machines, namely the Krups Pixie XN3006, the red one. The pixie model is made either by Krups (German company) and De' Longhi (Italian company). The two versions can be recognized by the shape of the aluminium sides, and by the front.
The Krups Pixie machine has a red led which lights on whenever the water level is low. The sensor is optical and is located on the backside of the machine, near the base on the left, when looking from the top.
I noticed that sometimes the red led is on even if there's plenty of water in the reservoir.
There are three possible causes, so if you have this issue you can check whether these conditions applies to you:

1. Your machine is near a heat source, so there may be some tiny bubbles inside the water reservoir. Just use something like a long wooden spoon to eliminate the bubbles form the bottom-left part of the reservoir. The led will change to white as soon as you do this. Make sure not to scratch the plastic.
2. You cleaned the reservoir and there are some marks on the back of the reservoir. Use a soft tissue to fade the halos, and it should be ok now.
3. The reservoir is scratched in the bottom section. If this is your case, chances are that you need a replacement for the water reservoir. Call the Nespresso Club for assistance.

I hope these little tips can help you out!!