appreciate the replies. This stuff is nasty and with considerable effort the bulk of it can be scraped off with a plastic chisel-like tool. Still working on finding the best way to clean off the residue after scraping. The discharge definitely originated from the logo area, where I suspect the material used to fix the logos in place has deteriorated over time due to heat. The logo discs are covered with a layer of blackened similar material which has darkened slowly over the years. The semi-clear discharge comes from beneath the logos.