do you have to put oil in the top of the old kenwood chef?

In the middle of making icing my kenwood began to smell the kind of smell that makes you think something needs oiling.
I've found a place on the top that looks like it could take oil but I can't undo it, it's loose at one point and then goes tight, the same if you turn it the other way.
Can you help me?
It's a late 1950's model I think