I highly recommend the rinseworks bidet. It is designed much better than the one from the pic. You don’t have to shove your entire hand in the toilet to use it. https://rinseworks.com/

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I’ve gotten that as well. I have had success using rubbing alcohol on those spots. Also helps to use an alcohol aftershave.

OpenSuse Tumbleweed

We also need to consider the air that is in front of the train as it moves forward. That air is going into the portal at the rate the train moves forward and therefore coming out the other portal at that rate.