Tapes get chewed in VHS machines if there is a bad Pinch Roller. ( it is a black hard Rubber Roller about 1 inch high, found on the right side of the Video Head Drum)
The other reason could be a physical one - some dirt or lint on the Roller or the guide arms.
Un plug the VCR from the mains Power supply. carefully open the top cover (there should be two screws on either side of the machine, and one at the rear).
Now plug the machine ON, and load a Cassette tape and observe the guide path / arms, when the tape is unspooled from the cassette.
Observe the tape as it rolls from the left side of the spool, to the right.
I'm pretty certain it will be something mechanical - a foreign object like a broken piece of plastic, or some pin or clip which must have been inadvertently dropped inside. Eject the cassette and remove the foreign object. If possible, clean the Pinch Roller with Iso-Propyl Alcohol. Use a soft clean cloth soaked in the Alcohol.