W140 odometer not working

[MB140300SD]

I am working on a 92 300SD which has the analog odometer. The speedo works but the odometer does not. Assuming it was probably a broken plastic gear I googled to see if I could find info on taking the cluster apart. I came across a video talking about repairing then and the odometer not working could be electrical or the gears. He also mentioned the cluster can be a cause of a battery drain, which I do believe I have so I am now thinking I could have electrical problems and possibly a gear problem. I have rebuilt a few cruise control amps replacing the caps and resoldering the joints, but I am not sure if I can tackle this as he mentions replacing transistors. If it was just replacing the caps I would be Ok with it but I suppose I could figure out the transistors as well. Anyway, anybody been down this road before or know of a place I can send it off to and get it repaired?