Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question. I regret that I cannot offer Live Phone Call service at this time.
The problem is likely to be in the audio amplifier that takes the signal read off the tape and sends it to a speaker.
Try contacting this person, who fixes Teddy Ruxpin figures made in the mid-1980s:
I hope he can help you with the needed repair to the electronics of the figure.