I don't own a 388 myself but your descriptions of color don't seem quite right to me?
The erase head is normally a whitish/taupe color with black colored strips where the tracks are on the front of the head. I am talking about the head on the left side here. Is this head copper colored?
The next head is the sync head. This is the one that records and plays back. It is normally a chrome color with black strips on it where the tracks are.
Is the color uniform from top to bottom including the areas above and below where the tape travel? Or, is this discoloring only on the tape path?
If you are trying to remove stubborn oxide that alcohol is not removing, you might want to try using Methanol instead but be very careful with that stuff as it is incredibly flammable and burns invisibly!! Use it in a well ventilated room with windows and doors open and do not smoke in the room while you are doing this or you will be hanging with Elvis!
Perhaps posting a picture of what you have there would be helpful.
If you have a decent digital camera that has a macro mode to it, you should be able to get within 3 or 4 inches of the heads and put a light on it first. Don't use the flash as that will wash out the picture from that close a distance.
Ordinarily, tape shed and normal oxide has a reddish brown to black color to it. Not a copper color.
If you are playing old tapes that are shedding oxide badly, look into baking the tape in a food dehydrator at about 135 degrees for 3 to 4 hours. This should harden back the binder or glue in the tape that is in a semi-liquid state state and letting the oxide come off on your heads and guides too easily.
Cheers!
