PAN number is wrong in sale dead

Hi, I purchased a flat in Bangalore 4 years back with in a society.I approached with builder and he sold me one flat which was land lord share hence the deal happened bet ween me and landlord directly but builder did all paper work like agreement,sale dead and charged INR 21000. During the purchase everything went well and sale dead executed between me and landlord and witness as builder's manager. I took loan from SBI hence original sale dead taken by SBI bank. Today , i was just checking my document then got to now that my (buyer) PAN number is wrong with one alphabet .It typing mistake and it written as "J" Instead of "I" . Could you please help me in answering my below question. 1. Is it necessary to correct it? 2. Will there be problem while selling in future? 3.During the rectification dead land lord(seller) presence is necessary in sub registrar office? 4.What to do in case unable to reach landlord(seller) or he do not want to come in sub registrar office? 5.How much would be total expense in executing rectification dead? 6.Is it ok if landlord give in written that I(buyer) can go alone and execute the rectification dead. 7.How much time it will take complete process? Priya