Dash light won´t work, need help!

No, the car wasn´t rewired. The dash was dismounted and re-installed cause of bad fuel gauge. After reassembling the problem popped up.
Fuse is o.k.
Dimming the lights only work on Pos.1
At Pos.2 nothing happen. It´s like on/off when pulling the switch.
Do you mean the round harness connector on the back? I will check.
Thx for advice!
btw a new switch is already ordered.