Canon EOS 30d – ERR99 – shutter problem

Thae 30d made after a few exposures err99. After off/on, shooting was possible again. At the beginning this appeared rarely, the more and more often.

I decided to change the shutter, so I ordered it.
After disassembling I’ve found the following in the body:

 

A spring on the motor… The motor’s body is magnetic, so it is a safe place for a spring – but who has forgotten it there? The owner told me, that the camera was never disassembled before. There were no signs of former disassembling. I didn’t found any “normal” position for that spring… Mystery.  Anyway, it should be not there.
After I had the old shutter in my hand (Old Shutterhand, Karl May) I tried to measure out, what is the reason of the err99.
Nothing.
I mean, it was not possible to measure any fault on the coils (ca. 74 ohm), and on the mechanical contacts (ca. 0,2 ohm).

I’ve mounted the new one. The body works perfect. Another mystery.

I have only one possible explanation: it could happen, that the coil has a temporary bad contact somewhere in the inside, which makes no problems for the ohmmeter which works with microamps, but makes an open circuit when the normal current (a few ten of milliamps) is flowing.

Anybody any ideas? Don’t hesitate, i’m waiting for Your answers.

János