I did a really amazing sound art course with Graham Dunning back in 2014. Part of the course looked at modified record/extended turntable techniques. This shows some of the ideas of cutting records in half and glueing them back together as well as modifying the records with tape or sandpaper etc in some way. Loops can be created by tying a string and to the tonearm and then tying off the other end off to restrict the movement of the arm.
Matthew Reay 