Offizieller Kommentar
Hi German,
The red parenthesis around the player number simply indicates that player is "on air" (the channel of the mixer it's connected to has audio going to the master in some capacity).
As for the jog adjust, it is a mechanical tension adjustment and can vary from player to player and over time. It can be adjusted internally, however we do not recommend users perform this adjustment themselves (as we are unable to provide the detailed instructions on doing so), and would direct you to contact an authorized service centre in your region for assistance.