Our mutual friend turned down attempting repair on the pedal, because of the "tiny internal parts" as correctly predicted by knowledgable folks here.
Another place also refused to repair it after he told them about the pedal.
Being a Boss fangirl, I encouraged him to buy a used pedal if available at a reasonable price. He found a used DD-3 with its back plate missing listed on a store's website for 60$. Our mutual friend said he will surely find a replacement for the missing back plate.
Thank you for helping out.
Brianna