Hi All,
I was looking on the web for any pictures or drawings of the inside of the SLA since I might have a problem with mine. I couldn't find any info about the internals. Most posts are about how a drink was spilled on the SLA, and it stopped working. I was wondering why a spilled drink could ruin the electronics - most electronics are conformally coated to protect them. I went to a pick a part to find a SLA. I couldn't find a crossfire or SLK SLA, but I was able to pull a 2002 CLK 320 one. I think it should be representative of the crossfire SLA. Taking it apart was fairly straightforward, except for the part where I opened the small box that contains the slide contacts - the plastic tabs were extremely brittle, and I broke most of them. Anyways, I think the reason spilled drink can ruin the SLA is that it gets inside the slide contacts (Figure 3 in the attached PDF), isolating the contacts thus preventing the SLA from knowing what gear it is in. Of course, the unfortunate part is that the slide contacts are the last thing that comes off. The white gear looking piece actually is captured by a pin that protrudes from the D profile tube. My guess as to how it works: as the tube rotates, the captured pins move the slide contact. There are clear spots on the rails at different points, so when the slide makes contact at those points, different pins are shorted together (the pins are to the left of the picture). The pattern of shorts or resistance differences corresponds to the position of the shift lever.
Hope this is helpful to someone.
-Jerry