Attached are plots for Si-pad 2 with hits from ionization of 206Pb81+ at the target.
The plots are representative for all Si-pads, the pattern is always the same!

y-axis: E n-side
x-axis: E p-side strip
condition: E_gate on peak in CsI

While strips 1, 2 and 7 look fine, strips 3 and 6 show already signs of degradation. 
For strips 4 and 5, it is clearly visible that something is wrong.
Those are the central strips, which probably see the most rate.

The same dataset was analyzed here: https://elog.gsi.de/esr/E121/62

This might be a hint to a radiation damage or to the fact that we operate at too low bias voltage (32 Volt).
Maybe it recovers if we increase bias to 60 Volt.