I have the same issue with a white KMC 1 which I bought brand new in 2014. Over the last few years the entire surface of the white plastic housing started to accumulate a very sticky messy residue all over it. Every square inch of the white plastic had this sticky junk all over it. I wasn't sure what to use to remove it, so today, I used several paper towels with a small amount of Windex on them. I know this was probably not the best thing to use, but it took off all the sticky yellowish junk off. I had to keep rubbing and applying more windex on the paper towels, but eventually it did break down all the surface residue. I was careful to keep the sticky residue that came off from getting on the front and back black grilles. as well as not get any moisture on the grilles, or the control panel on the top. I know it doesn't look as good as when it was new, but it looks a lot better now with all the gunk removed.
I haven't really used this Klipsch KMC1 speaker that much over the last few years. I was listening to some music on this Klipsch about 3-4 years ago and I heard a large pop sound and then there was a burning smell, not sure what happened. But today after cleaning the entire outer casing of the the Klipsch KMC1, I charged the Klipsch, and it charges just fine, Then I connected the Klipsch to my phone and bluetooth still connects without any issues, as well as all the other controls work fine, just like they used to. It still sounds great, so I am not sure if possibly one of the speakers blew and it still sounds good with the remaining speakers working, or what happened to it.
I have stored the Klipsch speaker on the TV shelf in the living room for the last couple years, so it has not been exposed to any harsh weather or elements, and I have not really wanted to use it, in part because the outer surface was a complete mess with the residue all over it. I will have to see if the gunk comes back again, and maybe it needs to be wiped down occasionally. The KMC 1 was definitely a great speaker for listening to music, preferably at louder volumes I really have enjoyed it, and maybe I will see if I can keep using it for a while longer.
