Rhodes Chroma Polaris

Hi Guys,

This problem happened before, about a year ago.  

One of the keys weren't working, and I thought it was just out.
Then I opened the top panel regarding another issue, and closed the
panel, and then the key started working again, keep in mind, I didn't
touch the key.  I just assumed it was a fluke.

A few years go by, and now, certain keys randomly don't play, then
they play, then another one doesn't play.  I'm looking for a pattern,
but I'm not aware of the issue. 

For instance, if C1 key goes out for a second, I'll press C2, and C2
plays just fine, so it's not a voice thing?  Wouldn't that effect all
of the octaves.  The all of a sudden, C1 works fine for a while, then
it's G1, and G2 is fine.

Does cleaning the contacts effect if the MIDI signal triggers the
sound or not, or is it just internal?

If so, how do I go about cleaning the contacts, if not, how do I go
about fixing this DIY?

Thanks