900 II, door lock rear left broken – who knows what?

Hello, since the day before yesterday, unfortunately a door lock on our 900 II 2,3 SE – BJ 96 is defective. If you open the left, rear door, you can no longer close it after that, i.e. the locking mechanism in the door is apparently stuck in the wrong position and then beat hard against the locking device, if you want to close the door – the door does not fall into the lock and can not be closed completely. With a little grope you get the bar with the screwdriver again. n the right position, so that the door closes again – the game starts again from the front at the next opening. Practically the whole thing happened to me for the first time the day before yesterday during the interview, so that after the conversation in a good suit I knelt around the SAAB door, when my potential boss just came out of the office 😉 I then provisionally fixed the two rear doors on the handles with a tension belt and drove home – has little At home I got it again (see above) but at the next door opening it was like before. I had already removed the door panel, but could not notice anything – but I am also no SABB lock professional and don’t really know what to look for – but would like to avoid a visit to the workshop because of such small things. Central locking and door handles inside and outside work normally. Does anyone have an idea ?? Thanks and Gruss Martin