My teddys eyes and mouth won't stop moving

If its an original 1984 teddy ruxpin, you have to use his exact WOW tapes, they will say Teddy Ruxpin on them, if your using any other tapes it could trigger the servos to move rapidly. If you are using Teddys WOW tapes, it could either be that the tape is messed up/stretched, or that the servos are out of sync, due to wrong signals from the cassette deck, (like having dents in the pinch roller). You could try and hold teddys jaw shut, and only remove your hand when its teddys turn to talk, maybe after 2 runs of doing this, he’ll go back to normal. The teddy ruxpins tapes:

The potentiometer on one end of hid servos that cause eye and mouth movement need to be cleaned with Deoxit or alcohol.

Once cleaned up, the unwanted movement will stop.

Make sure all parts are completely dry before running his servos.