Not all stolen instruments are listed on the IDRS registry.
Be certain to ask for the history of the instrument and obtain a copy of the insurance policy, or an equivalent document certifying that the seller is the legal owner of the instrument. This is especially critical if the seller listed the instrument on ebay, or originally purchased the instrument on ebay or another equivalent site.
“…The insurance company would be very interested in knowing about the recovered instrument — it has subrogation rights and can pursue the claim. A thief cannot pass good title, so the buyer is at risk of losing the bassoon to the insurance company.” IDRS Legal Councel, Jacob Schlosser