bar not oiling on my electrolux petrol chainsaw?

Electrolux MAC 335 (Ecopi Italy Type III Ser 530 057701)

The bar is not being fed with oil. Oil in tank but I don't understand how it gets to the bar. Close to clutch under the bolts holding the bar in place is a small platic rt angle connector attached to a short length of flexible 'rubber tube'. If I pull this connector out then oil appears in the hole it came from in the plastic body of saw.The flexible tube from this runs to a square topped rubber 'device' which looks as if it should pull out of the body but it doesn't. Blowing down the flexible tube does nothing.

It might help if I understood how it was supposed to work eg. where and how the oil gets on to the bar etc.

Many thanks