Noblex 135u - using filters ?

I am having a problem with my Noblex 135u when attaching filters. I follow the manual instructions to set the camera to Multi-exposure, press and hold the shutter button, and rotate the turret clockwise till I can slip the magnetic filter onto the lens.

I understand that this should result in the light curtain covering the turrets “slit” to avoid eating an exposure. This is how my 150s and 175 s have worked. But this camera does not close the slit when following the procedure, so every time I mount or remove a filter the frame will be exposed.

Are there any Noblex gurus here who can advise me in this? I suppose I will need to send it for service, or just lose a shot each time I mess with filters.

Thx

I am sorry to reply so late, but I may as well post the answer for the benefit of anyone else who finds this thread...

There is a key step you must do... You have to tilt the camera forwards. It may sound unlikely, but this is required for the cover to fall into place correctly. I don't know how this feature was engineered, but I guess it relies on gravity somehow. This instruction is actually present in the German-language instruction booklet, but the translator who compiled the English-language version seems to have decided to omit this important step.

When you tilt the camera forwards, listen carefully - you will hear something falling/clicking into place. There's a cover over the slit in the drum, and additionally some kind of "lock" so that the drum will only rotate enough to install/remove the filter, and not the full way.

So...
1. Switch camera off
2. Set double exposure switch to M
3. Hold the camera upright, with the lens slightly tilted forward
4. Press and hold shutter button. Turn lens drum clockwise. Release shutter button
5. Insert/Remove magnetic filter
6. Turn lens drum back
7. Reset double exposure switch

I had a Noblex 135S for 20+ years and loved it. Unfortunately it was stolen in Italy early last year. Serial number 104790.