A return request does not necessarily mean that you have to return the item. You just have to wait for the seller's response first. If something is missing, the seller could offer to send the missing part or could offer a partial refund for example.

I understand that the term "return request" can be a bit confusing. I was once in a similar situation, but then I read more and realized you first just have to wait and see what the seller says. You can then either accept or reject the seller's solution. I think that if a seller can solve a problem without asking for an item to be returned, they will, considering they have to pay for return postage.