Hi Marcus. Sorry for the delayed response. I've been studying your response, doing research to find wafers (spades) and repairing what I think I can while waiting for parts.
I've ordered door handle pads from Mr.Fiat and striker shims from one of my local MB dealers. I've found wafers, but in doing so, realize that I shouldn't need them for two reasons. Firstly, the source sells only to locksmiths internationally, so any decent auto locksmith should be able to fix and re-key my locks if necessary. Secondly, it should not be necessary for the following reason. Using a spring assortment from Canadian Tire to get the right spring steel material, I straightened a small spring with the right wire diameter and rewound it to make a mirror image of the spring on the passenger side. After installing it on the driver's latch, it works perfectly, allowing me to lock and unlock the driver's door from the inside, after tricking the little latch tab to make the latch believe that the driver's door is closed. In fact, the latch is not even installed. I removed it for problem diagnosis.
Maybe what i'm describing next is as it is supposed to be, but my passenger door will lock from the inside even with the door open without tricking the small tab in the striker receptacle. However the driver's door must be closed against the striker to lock from the inside. I must have misunderstood Alfred's explanation about the inside lock button function. I thought both door inside locks functioned the same to prevent lockout. Oops! Alfred said it but I missed it. He specifically said the driver's door must be closed to lock the door from the inside. Sorry, Alfred. You were right as usual. I should read more attentively.
Regarding the wafers, I was sure I had one of more broken wafers because my door key only worked on the passenger side, and even then, not well without jiggling.
It turns out that I confused my door keys with the two keys from my new fuel cap. When I realized the confusion, I went inside for my other key ring and found the door keys. The door locks work OK with the right keys.
At this point, I'm waiting for the door handle pads and the striker shims. The pads are supposed to come from Atlanta, Georgia and the striker shims from Stuttgart. Additionally, there are rumors of a postal strike coming here in Quebec, so I'll be thankful, be patient and think about the people who will be victims of Hurricane Florence.
Winter is almost here and I've got all winter to finish the car in a heated garage,so I'm blessed.
Thanks for your help, including the links to the other threads.
Tom Kizer
Levis, Quebec, Canada