Mortgage Deed Without Possession In EC

I am buying a plot in Chennai. The parent owner has a mortgage deed without possession with the scheduled land mortgaged to a Co-operative bank in 1992. This document is reflected in the encumbrance certificate. The builder/promoter shared the loan clearance certificate issued by the bank in 2006 to the parent owner mentioning the mortgage deed number, property details and also mentioned that the loan is cleared and the property is free of encumbrance. However, the same is not reflecting in encumbrance certificate that the loan is cleared. Also, there is no registered document or deed to confirm that this mortgage has been cleared. The builder/promoter has bought this piece of land from the parent owner in 2017 and patta is now in the name of the promoter. Shall I proceed with buying this plot from the promoter.