I found two problems:
1) the number pad works sometimes with num lock off
2) control + alt + F1 does not work, while F2 through F7 works perfectly.
Thank you for your attention.
CTRL + ALT + F1 does not work, going to one of tty2 and tty6, to switch to tty1 just use ALT + F1, Ctrl, you can omit.
Found this site:
Switch to the first text terminals. Under Linux you can have several (6 in standard setup) terminals opened at the same time. This is a keyboard shortcut, which means: "press the control key and the alt key, hold them. Now press <F1>. Release all keys."
Switch to the nth text terminal. (The same could be accomplished with the rarely used command chvt n. "chvt" stands for "change virtual terminal"). In text terminal (outside X), you can also use <Alt><Fn> (the key <Ctrl> is not needed).