[sdiy] Strange behavior from my MG-1

[DTK]

Hi all...

I've recently noticed something odd with my MG, so I thought I'd see if
anyone has any ideas...

If I hold down 2 keys that are close together, I can hear a "bubbling"
noise... I know that's a pretty poor description, so maybe I'll try to
record and post it if anyone's interested.  It's irregular, but definitely
cyclical, and it varies depending on the proximity of the keys I'm pressing.
If the 2 are side by side, it's fairly fast, and as I move further apart it
slows down.  After about 4 keys, it's no longer there.

I had never noticed it before, but I was just goofing around trying to play
some quick trills and it came to my attention.

Can anyone point me in the right direction here?

Thanks

D