BTC foam and foil - is this normal?

[DarkBRl]

I've got a 30 years old BTC-5339SX, a foam and foil linear keyboard, this is the first time I'm using a mechanical keyboard, and the first time i'm using a linear. The problem is that something seems wrong, the typing sensation it's not good at all, since I've never used something like that i don't know if the foam or something in the keyboard isn't working properly anymore or if i'm just not used to this type of keyboard yet. There is something wrong with this keyboard or it's just like that?

Thank you.

[xxhellfirexx]

The foam might have disintegrated and you are bottoming out on the plastic sliders.