Not to worry, coastie. Your Rumble is working just fine. As Johnny Stevie says, you have discovered the "hidden mute feature", as we have come to call it here in The Club, and documented near the bottom of the Rumble Talks section of the Rumble Club Wiki page, linked in my signature. It is a very handy mute, especially with a footswitch, if you never use the Overdrive. Also, the manual says to use the Level control to balance volume levels.
On the subject of "effect" vs "circuit" vs "channel" I side with either "effect" or "circuit". The manual calls it "the Overdrive circuit", but I think of it as an "effect", too. And, to me, a "channel" includes the EQ controls, bass, mids & treble, such that switching between channels can give the different tones based on those different EQ settings without the use of any other effects or circuits. Rumbles don't have that, nor is such mentioned in the manuals.
That's my tuppence, anyway.
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Thank you so much John Stephen, G-Dog and Chupacerveza
Much appreciated.
I knew in my heart of hearts my 500c was okay (it sounds too damn good to be faulty
Regarding the "use of the Level control to balance volume levels" in the manual, I misinterpreted this to mean to balance them together whist both were heard together (stacked) at the same time. Oops!
What's not to like about a handy muter?
Thanks for this folks. Much appreciated. Rumble on !!!
Stay safe and remember to Self-Bassilate

