Lack of power on M13A engine

I've made the tests with the wheels - videos here photos.app.goo.gl/otcXvx8yKfe2GCjA8

Conclusions:
- weird sound coming from the right wheel (as you can hear in the videos)
- the interior of the braking disk was hotter on right side compared to the left (40 celsius vs 36 celsius) and even after a couple of minutes, there was still a 4 degrees difference (21 celsius vs 25 celsius)
- the temperature was measure on the interior of the braking disk on each side, on the exact same spot (photo from the top of the wheel image.prntscr.com/image/zbmGurcHSeygUwomaOMUGQ.png )
- not sure how much time the front wheels should rotate freely
- the back wheels rotating only when doing it by hand (logic, because they were connected to the transmission)
- forgot to measure their temperature too...