I have a 1986 560Sl with electrical problems

One problem recently started with me intermittantly blowing fuse #13 which protects the car alarm, all interior dash lighting,the right rear tail light & the plate lights. After unsuccessfully tracing the problem and eliminating plate lights and tail light and that wiring, the intermittant fuse blowing stopped, but I now have no light in the left gauge cluster, the outside air temp gauge, the A/C control buttons, the hazard warning switch or the row of switches above the radio. I DO have gauge lights working for the tach and the speedo, but dimmer control will not change brightness from full bright. Right tail light and plate lights work fine now also.
I would like to get all interior lighting working again. Looking at the MB electrical troubleshooting manual, it appears that my problem MAY be in the instrument cluster wiring itself, but don't want to go there if it is not necessary.

My other electrical problem revolves around the right high beam headlight. It does not work. I have disassembled the headlight electrical looking for problems after determining that the fuse for that light was not blown. I can find nothing amiss except that I have no voltage going to that headlight on high beam. Someone suggested the dimmer switch may be bad. Is that possible? Does anyone have any knowledge of other components that I should first check? How do I get to the dimmer switch to check for voltages?

Thanks for your help.