Ah! Thanks Rolla, Deejay. Something so basic can cause grief!
Re bearing caps, only the left hand side has a grove. My chassis is pre 1980 and the caps have grease nipples! Every time I see them I have to remind myself that they are sealed bearings and don't need to oil them!. Either way, I'll swap the washers around and see if it fixes the problem.
Thanks again.
