ScanMaker 3600 stopped working

[Dorian Büttner]

Hello,
I configured Microtek ScanMaker3600 succesfully under 5.3-Release. So 
far, so good.
In between, I upgraded to -stable and suddenly had to notice that when 
starting the prescan, the bulb isn't moving but keeps kind of knocking 
at the front of the case.
The scanner uses the sm3600 sane-backend, libusb is 0.1.7_1, which 
appears to be reasonably new.

Controller /dev/usb0:
addr 1: full speed, self powered, config 1, UHCI root hub(0x0000), 
VIA(0x0000),rev 1.00
  port 1 addr 2: full speed, self powered, config 1, product 
0x40ca(0x40ca), Microtek(0x05da), rev 0.00
  port 2 powered

Anyone an idea what might have happened?
Greets,
Dorian