Assumption for filing this issue that it might be related to an issue with collision detection with the background or/and sprites.
When "Thing on a spring" is played to the second room on the right the escalator which usually leads to the thing going up is not working. Thing on a spring stays on the floor.
Also touching the "transporter" button which leads to the thing being moved to the end of the room has no effect.
Correct behavior can not be seen in any available emu but on a gameplay video available e.g. at https://youtu.be/QhkFF0c-gUo?t=43.
Is this ?

Using the ladder on emulators:

...go left from the main screen and pick up the gift (see arrow), you cannot use the ladders or escalators if you do not pick up gifts !!! This is not an emulation problem or other, only a playing rule !

Thank you so much - will close this issue as quick as possible...
saved my day to show this to my kids...
Thank you so much - will close this issue as quick as possible...
Don't worry. Please open up issues if you experience problems. We are happy about all bug reports. If it turns out that a bug is a not a bug, it's not a problem.
Too difficult game, but it works well on VirtualC64, thank you
Most helpful comment
...go left from the main screen and pick up the gift (see arrow), you cannot use the ladders or escalators if you do not pick up gifts !!! This is not an emulation problem or other, only a playing rule !