I´m customizing the first page in Mach3 and have removed all that I think is not necessary and not I´m not able to jog with the keyboard on this page anymore.
What is enabling the keyboard jog on the different pages?

You need a Jog On/Off LED on the page.

So it was that simple, I looked at it in the screen editor but I could not that it did anyting by itself, is it just Mach3 that looks for the LED and then enables jog?

I think it might be a Jog On/Off button, rather than the LED.

I know it's one or the other, but I can't remember which one.

Not sure how it works, but you just need it on the page.

Ok I placed both on the screen and now it works, thank you very much.