Wire unit Dowser disconnected from the Signal Backplane.

Reconnect the blue wire unit of the Dowser with the Signal Backplane.

Blocked blade of the Dowser

Check if noting is blocking the blade of the Dowser. Do NOT force the blade from the open position to the closed position or vice versa.

Damaged wire unit of the Dowser

Try to repair the damaged wire unit. If not possible replace the Dowser unit. See "Replacement of the Dowser (Shutter)".

Malfunction motor of the Dowser unit

Replace the Dowser unit. See "Replacement of the Dowser (Shutter)".

Malfunction Fan Control board

Replace the Fan Control board. See "Replacement of a Card Cage board".