The winning rocking horse!
The allegory aspects of the story would be the whispers of the house and the transfer of money worries from the mom to Paul. I’m not quite sure what to call it financial woes, or the voice to desire, or maybe even the voice of the devil, could all describe these whispers. Also the idea of luck was an allegory, the mom and dad didn’t have it but
The main symbol in the story was the rocking horse. Paul rode it till he found luck. I believe the rocking horse was like an oil well. It was there to help the family survive brought them life, good fortune, prosperity, but it was not endless. The final ride was like the last of the oil being pumped out. It was the ride that counted for the most, that helped the family out the most, but it came at the cost of the son who made it all possible. The status of the rocking horse reflected the health status of the Paul also.
Sorry but I didn’t see anything else, ether symbols or allegories.