The lien on a piece of equipment such as a tractor is almost always a UCC lien. If the lien no longer exists, the lienholder should be able to provide something in writing stating the lien has been satisfied. In general, lienholders are very prompt to perfect liens at inception of the loan and very slow to process lien releases at satisfaction of the debt.
About the only advice I can offer is to stay on them until you get written confirmation of satisfaction of the lien and if you can’t get it within the 10 weeks, contact your state Attorney General’s office for assistance. Communication with the lienholder should be in writing (email, etc.) to the degree practical, particularly after the 10 weeks. Perfecting a lien and refusing to release it, even if the refusal is implicit via unreasonable inaction, is not legally acceptable behavior.