I have an 86 300SDL an I can not insert key into lock on drivers side door. It was working fine this AM, when I ran numerous errands. I got out to lock door to no avail. I do not think anyone had put anything into lock, because it had worked fine at 3 or 4 previous stops.

Any suggestions would be appreciated. The passenger door works ok, and I am using that until I fix problem.

Try giving it a couple of shots of WD-40, continuing to attempt to work the key into the lock. It sounds like a stuck tumbler or the little cover inside the lock cover is stuck.

I tried the WD-40, but was not successful. Any other suggestions. How difficult is it to remove the tumbler?

Since you can get into the car, you will have to remove the door trim panel on the driver's door, the handle and trim from outside, remove the retainer and linkage from the lock cylinder and pop it out of the door. But, before you do that, try some powdered graphite into the key slot. Does the key go in at all? If you look at the lock, there is a little metal plate on the inside that closes over the opening when the key is not in there. Can you see that? If you can't see it or it doesn't move, then it has broken and is jamming the track for the key.

The cover on my lock cylinder broke and is jamming the track so does that mean I need to buy a whole new lock cylinder or is there a way to repair this. It looks like the little springs broke off.

I did a search and read that I can take the assymbly from the other door and put it on the drivers side door. If it is possible to repair the lock cyclinder what would be the best thing to do, fix it or switch them?