See MikeD's post above. There are 2 big posts on the solenoid. The lower one is what the motor terminal connects to. The battery + terminal connects to the other. In this configuration, nothing should happen. To activate the starter, use a heavy piece of wire and jumper the battery + terminal to the small terminal. The solenoid should pull in, the motor should run, and the Bendix assembly should be flung out to engage the ring gear.

The armature of the solenoid free-floats. It shouldn't be greased either, wiped with oil is fine, but don't grease it. It's usually only held in place by the rubber boot on some designs, or only by tension against the Bendix fork on others.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]