That usually happens when the jug is locked into the the wrong side of the base. With no blade and no jug, press a cocktail stick or a ball point pen into the hole in the base where the switch is and switch it on. Does it work?
https://www.google.com/search?q=FDP64+blender
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That kenwood is a UK model so if your in the US it's tough to source. The ring you need should have an outside diameter of 76 mm and an inside diamete of 56 mm.
This is a uk ebay link with the exact part.
1 Kenwood BL300 Blender Liquidiser Rubber Seal Gasket
This is a us amazon link with something that might work but not exact. There is a uk amazon equivalent if that works better for you.
Amazon com kenwood blender seal