Our washing machine an AEG 'OKO' Lavamat 610 is quite a few years old and
works fine apart from suddenly taking a liking to chewing up and tearing the
ends of some tea shirts.

Is there anything that can be done? What is the likely cause of this, do
you think?

Since the machine is five or six years old, I guess the cost of a washing
machine mechanic (in London U.K.) visiting would be uneconomic? Grateful
for any suggestions on the best course of action.