Polaroid Automatic - Zeiss Ikon Rangefinder problem

[JGOB]

Hi,

Could anyone please help me out with the following issue:

I just got myself a polaroid automatic 350. Everything was working fine. Focusing, exposure, ..
But now suddenly the focus patch doesn't work anymore. Sometimes there's little movement but not even close to the full focus range. Parallex correction is working though.
Anyone have any idea what could have happened and hopefully how to solve it?

Thanks a lot!