Hi Tim:  There can be a number of things that add up to causing these  
problems.  It will help to put the tape into another better shell with  
rotating guides.  This will reduce friction by getting rid of the  
fixed posts.  Also the rotating guides  are grooved and provide much  
better tape guidance for winding than a straight post which allows the  
tape to slide up and down its non-grooved  surface and thus cause very  
uneven pack winds.

Another issue is whether or not the pack winds of the cassette are  
smooth packs or if there are a lot of popped strands with uneven  
winding.  The very thin C-90 tapes tend to have popped strand type  
uneven winding which makes them have a friction event with the shell's  
surfaces, putting extra frictional drag on the tape pack. This makes  
for a greater frictional load on the spindles of the tape machine  
trying to turn the cassette tape hubs and move the tape through the  
cassette mechanism.  A test for this is not  only visual, but when the  
tape comes to a halt, one can find out  by taking the tape out of the  
tape deck and attempting to turn the hub manually by hand to see if  
it  is hard to turn.  If so, then frictional events in the shell with  
the pack winds and posts should be evident.  However, if and when the  
tape is put in a new shell be aware that sometimes there are physical  
differences between various makes of hubs and shells. Some  
combinations work well with low friction and no problems while others  
do not.  The plastic slip sheets do a lot of good to help assure  
smooth tape winds and lower popped strand winding.  If  shells are  
changed, another thing to do is fast wind the tape several times from  
start to end to attempt to get smoother even pack winds and thus  
reduce uneven pack induced friction with the shell surfaces.  One  
might start out with the new shell slighly loose and the screws not  
tightened down completely at first so as to  not jam the shell or slip  
sheets down tight against the popped strand tape winds on the hubs.   
As the several winds get more even and smoother,  then tighten up the  
shell screws to completely close up the cassette shell.

Another issue is the tape machine itself.  What is the torque of the  
spindles of the tape machine?   If the spindle torque is low, it may  
be fine for tapes that do not have any problems, but when the friction  
goes up, as in this case, the torque of the spindles may be too low to  
move the tape of the problematic C-90s.  In that case, try another  
cassette machine and see if it has higher spindle torque.  If it does,  
that might make the tape move. One might be able to adjust the spindle  
torque for higher turning power, but then this may get too high for  
tapes in good condition and could get outside manufacturer's  
recommendation.  If you do not want to get into the spindle torque  
issue, then perhaps a solution is to use an object, such as a drill  
bit, and a hand drill, and very carefully wind the tape manually a  
time or two to get the popped strand problem solved.  Once this is  
done the tape should work well, provided it was not already badly  
warped, edge damaged, or is newly stretched  by forced remedial  
efforts to wind it properly.

Its unlikely the tape has dried out and is sticking to itself.  Recall  
that with cassettes, the oxide faces outward and its only major  
frictional event is at the play and erase heads when in the record or  
play mode.  The bare base film of the tape is touching the posts and  
guides, not the oxide coating. Cassette tapes almost never have carbon  
black back coating, so its goo not around to cause friction  
problems.    Lubrication is not recommended because it does not  
address the above mechanical friction issues.  It is likely to make  
matters worse and get all over various surfaces.

Hope this is helpful.        Charlie Richardson

On Jul 13, 2008, at 9:51 AM, Tim Brooks wrote:

> My apologies if this has been answered in the past, but can anyone  
> suggest
> how to get Scotch Master 90 cassettes that are sticking to play  
> through at
> least  once for transfer to a new medium?
> These are consumer cassettes from the 1970s or 80s in which the tape  
> winds
> around a fixed (not rotating) metal post, across the recording/ 
> playback pad,
> around another post at the other corner of the front of the shell,  
> and then
> back  to the takeup pack. The tape stops dead repeatedly, especially  
> in mid-reel.
> There does not seem to be any evidence of flaking and when  
> disassembled  (the
> shell is held together by phillips head screws) the interior is  
> clean. My
> suspicion is that the tape has dried out and is sticking either to  
> itself or to
> the metal posts. I've seen some suggestions that problematic  
> cassette tapes
> be  lifted out and placed in a new shell, but would this help if the  
> tape
> itself is  the problem? Would some type of lubricant work?
> Thanks for any suggestions.
> Tim Brooks
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