Mr Ian Primus <ian_primus at yahoo.com> wrote:
  As I have been collecting computers, I have noticed
 that some pieces of equipment like printers and the
 like, contain a lot of this awful foam stuff, most
 likely for noise deadening. Time has caused this foam
 to break down and turn to gunk, or at least a soft,
 squshy material that does not spring back. It also
 crumbles. IBM foam seems to be the worst, along with
 the foam used on Zenith PC's, turning into a tarry
 goo.
 On the CDC drives I just picked up, the entire inside
 of them is covered in this foam, some of it is
 starting to come off, or has stuck to cables and such
 inside. A couple smaller chunks of it literally fell
 off one part of the cover, the glue only holding the
 particular particles of the foam to which it was
 attached, and the rest of the foam falling away.
 What is the best thing to do about this, especially in
 something as sensitive as a disk drive? Should I
 remove it? What's the best method? Is there something
 I can use to replace it?
 Also, for instance, inside the cover of the PDP-11/84,
 there is a thin slab of foam that has turned to crud.
 I plan on removing this entirely - vacuuming away what
 I can and cleaning the rest off with something - what
 will dissolve this? I know that trying to get the gunk
 from IBM foam off your hands is nearly impossible.
 Any ideas?
 Thanks!
 -Ian 
This is a common problem with classic cameras where it is used as light
seals. The foam also tends to eat away other stuff like paint etc. so it
needs removing.
Get rid of as much as you can manually, by vacuuming, picking it out
with tweezers from small spaces, scraping etc, then clean the remaining
gunk away with alcohol (ethanol) which dissolves it instantly. Take care
with plastic surfaces, they may be fogged by the alcohol.
For classic cameras, new, better foam is available to replace the old
stuff. I have no idea of the price or where to get it from, try asking
Jon Goodman (jon_goodman at 
yahoo.com) who sells it in kits to reseal old
cameras.