I tried new batteries, disassembled it, and greased it. The engine wheels seemed a bit sticky due to something sticky inside that got there at some point. I put some WD40 to make it work better and was hoping it will work fine. It goes up the bridge easily on its own. Then I tried with one empty platform, pulled up so so. Got stuff on the platform, and that's it - it stops in the middle with no gear sounds or etc.
Originally it is with 2 wagons/platforms and it does seem to reach the same place and gets stuck in the middle of the bridge going up, and does not get stuck elsewhere.
Should there be some kind of clutch, or does it switch off the engine due to Amps raising?
I found this with gear sounds and can't relate. I examined all gears after disassembling similarly like in the video, except I could not pull the wheels off - felt like it will break if I pull harder. I did not want to risk it too much.
I tried looking around for engine pinion issues and stuff, but can't relate anywhere to what I'm experiencing. I bought it used. It's a bit disappointing to pull it/push it uphill, but so far my son doesn't mind too much :)
However, having a DIY soul, I'm a bit sad and insulted with situation...
It's a pinion issue, after thinking it through, disassembled once more and the engine spins, with wheels and accordingly pinion - blocked so will go for a metal solution, like here.