Do you know anything about the bikes history? Could the tensioner have been changed for an early Gen2 tensioner.
If the tensioner looks like this it is gen1:
https://www.ebay.co.uk/itm/335245917836
If it looks like this it is Early Gen2:
https://www.ebay.co.uk/itm/235495471612
The early Gen2 tensioners are considered a worthy upgrade for Gen1 machines