I would pre test Isopropyl Alcohol before using it to clean the knobs and markings as I have had alcohol based solvents soften plastic knobs, and fade coloured plastics used for the knobs and soften screen printing on front panels.
Personally I would remove the knobs and give them a good soak in hot water with dish washing detergent, wrap them in a tea-towel and then swing the towel around a few times to dislodge the water (which gets down the holes for the shafts). then allow to dry for 24 hours or so.
- note I suggest you do this in the bathroom with the lid of the toilet down as it does spray a bit of water around and if any knobs escape from the tea-towel and you are outdoors, they may be a bit difficult to locate afterwards....
There does seem to be some dirt on the front panel, I have found Eucalyptus oil is usually the most benign effective cleaner for front panels - although cheaper Eucalyptus oil is often mixed with Isopropyl Alcohol so check before buying that it is pure Eucalyptus oil and as always, test on an inconspicuous section of the front panel before cleaning the whole thing.
I use Eucalyptus oil (and the above method for cleaning knobs), on mixing consoles where you do not usually have the luxury of spending several minutes lovingly scrubbing each of one or two hundred knobs....
They do end up smelling of Eucalyptus though