I have a 1985 300td with frozen driver seat height adjusting rails. I removed them along with the driver's seat in an attempt to take them apart and clean and lubricate them.
I can see 2 pairs of rollers/bearings inside the sliding rails and they are corroded and frozen. Squirting PB blaster down the rails has freed up slightly the rails but movement is still too tight and requires a hammer blow to slide the rails at all.
How can I take these rails apart to get at the rollers inside? It looks as if mercedes stamped a couple of stops on the rail surface to keep the rails from over extending.
Has anyone been able to slide the upper and lower rails apart from each other or freed up a sticky height adjuster?

I recently pulled out my driver's seat to rebuild the padding and fix broken springs (will post photos). My height rails were similarly pretty frozen, though I found you must slide them to get at the bolts which attach the seat to the floor (confused me for a while). I worked them back and forth using WD-40 and other solvents, and soaking overnight in diesel fuel. I never got them where you can slide easily by hand (not much to grab hold of), but did slide with slight hammer taps. I greased with bicycle bearing grease. The seat slides up and down fairly easy in the car now. I didn't see a way to take them apart, without ruining them.