Sounds like the control track is not being read.
If you are lucky it may just be a dirty control head.
Audio/Control Head (part H in the diagram).
On the face of the above part H, you will see two shiny strips, the bottom strip is the control head.
Otherwise, it sounds like something is causing misalignement or loss of tape tension over the control head. eg. the mechanism cannot complete it's full loading, due to gear damage or something jamming the mechanism.
(PS. or jammed in the mechanism - cassette labels seem to becoming fairly common).
Another common cause of those symptoms is playing back a cassette which was recorded on a different machine, with record speeds which are not compatible to the playback machine.
Cobweb
August 2006
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cassette recorders.