Simplify the following text for a Grade 6 native English-speaking person.
Original: Lembit Oll ( 23 April 1966 , Kohtla-J Ã rve â `` 17 May 1999 , Tallinn ) was an Estonian chess grandmaster .
Simplified: Lembit Oll ( 23 April 1966 â `` Tallinn , 17 May 1999 ) was an Estonian chess grandmaster .