MS 102 synchronization between the turning drum and the regrouping drum

hello,
i have a problem with my sm 102 which includes synchronization between the duplex cylinders ,
tho monitor showes the following message (surveillance de la correspondance entre le tambour de retournement er tamboure de regroupement) in english (monitoring of the correspondence between the turning drum and regrouping drum)

 

Hi can you take a Pic from the monitor??

However test this:

Immediately before and during the changeover, the sensor 2...nB64 checks whether the reversing drum has reached its zero position.
At this time, the red LED on the signal conversion module SUM6 will go off.

Look for your schematic diagrams.

Blessing