Dan,
If you aren't using a dual capstan Nakamichi deck, I would strongly suggest
you source one and try it. Sometimes the pressure pad on an old shell slips
a little, driving the tape into the guide on one side, sometimes causing
friction and squeal.

Otherwise, on recalcitrant tapes, sometimes I would fool around with a
silicone spray mold release agent (spray). Just a tiny bit on a cotton swab
or foam tip, applied to the heads and guides (less is more). Sometimes it
would work, sometimes not, which then usually pointed to a problem with the
cassette shell, pressure pad, or slip-sheet.

Steve

Steve Greene
Audiovisual Archivist
Nixon Presidential Library and Museum
National Archives and Records Administration
(301) 837-1772

On Thu, Jun 7, 2018 at 4:06 PM, Marie O'Connell <[log in to unmask]> wrote:

> Hi all,
>
> I have been encountering random cassette tapes recently, mainly made in the
> Pacific Islands on random stock, which have benefited from baking for 12
> hours after squealing.
>
> They all played through without issue.
>
> Hope this helps.
>
> Marie
>
> On Fri, Jun 8, 2018 at 7:13 AM, Eero Aro <[log in to unmask]> wrote:
>
> > Hi All
> >
> > Unfortunately I haven't had time to follow this thread. Still, I'd like
> to
> > tell briefly about the other thread I started almost two months ago.
> >
> > I tried desiccation of Compact Cassette tape with silica gel backs. I now
> > have two Basf
> > LH Super red label cassettes in two air tight plastic freezing boxes. One
> > of the tapes
> > is in one box as such and the box is filled with silica gel bags. The
> > other cassette tape
> > has been removed from the shell and is in the other box with silica gel
> > bags.
> >
> > Unfortunately I haven't had the time to check the tapes. I will try to
> > find some time and
> > play the tapes to be able to tell if the silica gel treatment was any
> good.
> >
> > When I first time tried this desiccation process, just after 7 days of
> > silica gel
> > treatment the tapes played without squealing for about 30 minutes.
> >
> > Without the desiccation they played only about 30 - 60 seconds before
> they
> > started to
> > squeal. The squealing affects the audio badly.
> >
> > Eero
> >
>
>