Strange trails or (bad?) pixels  

Very likely yes, these can be bad pixels.

@vincent-mod Thanks for your reply... Is there any way to minimize them without darks etc.? 

You can try to use cosmetic correction in tab 2, switch the options on for hot pixels, I'm not entirely sure if that works without any calibration data (never tried that). Brin the hot pixel kappa down to maybe 2.5 or lower to make it more aggressive.

@vincent-mod Thanks! I’ll just give it a try... And maybe I’ll make some darks too... If they are bad pixels, they might appear at the same place anyway!? 

Yes that's why darks work. If you make some proper darks a BPM will be made automatically as well, this you can use on all your data taken with the same sensor. It removes bad pixels and never hurts the data, so always use one is my advice.

@vincent-mod from now on... I will 😉 Thanks for the advice!

You could try some retrospective darks.

Good suggestion Steve, you can try that indeed and make a bpm with those.

• @steveibbotson Indeed, I thought about that. I’ll give it a try!