I just sent a picture of the broken hinge (within 10 days of delivery) so I am hoping to receive the hinge or hinge+arm piece. From the HLJ policy page:
"If a return becomes necessary due to a mistake in shipping, shipping damage or a defect in the product, we will compensate you for the shipping charges to return the item to Japan if you ship the item as directed by us. All claims for returns or refunds due to shipping damage or manufacturing defects must be made within 10 days of its delivery to you."
[...]
"HobbyLink Japan is committed to customer service and will promptly address any customer claims of shipping errors, damage, defects, missing items, etc. if we are contacted within 10 days of delivery at trouble@hlj.com."