Kenwood 701 mixer, -- speed control fault?

- I am trying to repair a Kenwood A 701 mixer --The motor runs, but the speed control does not work.
I thought the big 450 ohm resistor would have gone,- but it shows as 462 so I guess that would be OK.
I wonder if it might be either the .1micro F capaciter or the Triac.
Before I start ordering new parts, any suggestions please ??