Heavy snow, a heavy passenger train, frozen sanders and an uphill grade may have been too much for this unit. Some carriages' brakes might have remained engaged too. Whatever it was, this unit had a hard time climbing uphill after leaving Varaždin towards Zagreb, Croatia resulting in the most amazing thrashing experience.
I did not expect that I will be recording anything on this trip, but hearing the loco thrashing while the train was not moving had to be recorded. I recorded this to the best of my ability in spite of the freezing cold, heavy snow (it is falling heavily, but you can't see it all the time because of the video quality) and ice dropping of the carriage's roof.
After crossing the uphill part of the route, the train picked up speed and we have arrived to the destination, albeit 2 hour late. 😄