
Everyone has different methods for stripping.
I use %91 Alcohol. It is easy to acquire and inexpensive. Plus it won't harm the plastic.

I use an old case lid.

Fill to just over the top and cover it. Helps reduce the fumes (if that bothers you) and evaporation.

Around the 3 hour mark things start to soften.

Around the 4 hour mark I start to brush and clean away.

Yes these are actually decals. Scalextric has changed to this method a few years back. Once these are off, the paint quickly goes away.
Hope this helps.