Yup. That's what I found accidentally into a BASF-EMTEC CEII. Looks that some internal part got broken and caught by the very reel, causing that weird aspect. Sorry for the low quality of this photo that I took with my phone. It can be seen that it's a plastic part from the very inside of the cassette. Stuff happens...
REally strange you mention this as i have a cassette that looks the same and i had wondered what had happenned...
that would have given me plenty of fun trying to sort that out....always used to have a spare shell or two to change tapes over if there was an issue...... have my little tape repair kit somewhere buried within my tape "hoard"....well that is what "Mrs Columbo" or `er indoors would say....