w124 trunk key problem
 

Does the w124 have a trunk key problem i dont know about?
I noticed on my 87 300d that the car key does not go into the trunk, therefore not open it, im not quite sure what the problem is, but yesterday my friends w124 87tdt wagon i noticed neither the valet key nor regular key will open the hatch trunk, is there a common problem with these locks in the trunk of the 87's?
Thanks
Ep

My daughter's '94 was having a problem with the trunk lock last weekend, she NEVER uses it but I wanted to show her how to lock it and disable the central-locking trunk lock.

The point being that lack of use is what I believe caused her problem.

The lock would not accept the key, maybe half-way.

Sprayed it (filled it) with PB-Blaster, went to dinner. Later I filled it again, worked the key until it went in, worked it for a while longer and it eventually turned (without forcing). After I had it turning fairly freely and ran the key in/out a few times, let it dry out some, and filled it with Mr. Moly Liquid Grease (my favorite lock lube), it works great now. I also treated her other locks including ignition, ... hoping it'll help in the future.

Pb blaster and Mr Moly on an ignition switch?
I was told by my mechanic never ever to use anything other than graphite.
Im confused.
But thanks

To add more confusion, my locksmith tells me never to use graphite.

Graphite is an Abrasive
 

The official MB Lock Lube is part # 001 989 26 51 10

No PB in the ignition, only the trunk lock to free the stuck tumblers.

Mr. Moly is good stuff, tenacious oil with MoS2. Graphite is good once, ... when the lock is being produced, but powdered graphite can build up in the recesses where the lock tumblers need to go, impacting them and causing the lock to not operate (bad thing). The liquid-based stuff will move around while you operate the lock.

Living in the rust-belt, my winter cars get lock lube treatments at least twice/year as preventative maintenance. With graphite they'd be toast before they're out of warranty.