Actually, they may need more than cleaning.
On my P6, cleaning did not bring the dead keys back.
The carbon pills on the rubber dome part of the contacts
had lost their conductivity. The PolySix is prone to this,
along with some other keyboards. In my case, the solution
was to paint the carbon pills with a conductive silver paint.
A small kit with the paint and several brushes costs $30
and is designed for just this task. I applied two coats.
You can find a video by syntegrator showing how to do it
on youtube.
But try cleaning first with isopropyl. Maybe you will
be lucky.
Bob
From: "mpe1969@tpg.com.au [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com
Sent: Friday, November 21, 2014 7:42 AM
Subject: [PolySix] Re: polysix still no sound
Thanks I'll have a look at it this weekend.