One of those small niggling issues
 

The trunk on my beloved 1985 300 TD suddenly refused to open. A local friendly mechanic gave the lock cylinder a whack and that fixed it...but it seems to also have ruined the cylinder which was not noticed at first. I have since: a) found the cylinder coming out of the casing; b) taking it out revealed a spring sticking out; c) a flashlight then showed a small ball still inside the casing. So... a) is the lock ruined? b) would reassemble of the spring/ball keep the cylinder in the casing? c) if yes to b), how the blazes to do that? Or plan z: look for a replacement (realize this implies a keying issue). If plan z: any part numbers? sources? (My searches have been futile!!)

You might try taking the lock cylinder to a lock smith to see if he can re pin it to match your key. Other than that the dealer may be able to order one if you give him your vin number. They should have records some where about what key code your car has. I know that is how you get additional keys.

I know that MB has tightened up their policy recently on replacement keys.

It is now necessary to order in person at the dealership, with the car and your title/registration in hand.

Locks and Keys
 

Although you can find used lock cylinders , bear in mind they're decades old .

The Mercedes Classic Center will sell you a new one with the correct key code and deliver it to your doorstep .

Just scan your registration and driver's license , send it to them ('Tom in Irvine Ca.) and sit back a few days .

They're quite handy for those odd ball parts some Dealers don't want to even bother looking up .

Given the cylinder was inoperative, I'd think that it was broken before anyone ( the mechanic ) touched it.

Thanks to all for the input and suggestions. @vwnate1, going down that road which seems to be the best solution as I especially want the key to fit everything.

Locks & Keys
 

Whilst you're at it , have them order you up a pair of new Master and Valet keys , use them or make pristine copies from them , this way your locks won't get beat up by worn out keys .

For a long time The Classic Center wasn't selling Valet keys , they are again so grab while the grabbing is good .

I find that even with shipping parts from The Classic Center are cheaper than from any M-B Dealer , usually faster too ! :) .

You read my mind. The guy we got the car from didn't provide a Master key and we got tired of using unpristine copies so we rolled them into the deal - thanks again for the help!

Sweating The Little Things
 

No mind reading necessary ~

I've been working on old cars since the 1960's and I dislike things that don't work or are broken .

Most have shinier cars than I do but few have better working ones , or can hop in at the drop of a hat and take a 3,200 mile road trip with ease and confidence .

We're very lucky in that Ma Benz cares enough to make some profit off their older models by supplying parts .

I remember you from other forums, including a VW one a while ago.

Hopefully in a good way...... :) .