It's a Gaggia Classic and it's 3-4 years old. Works fine other than problem described. Descaled and cleaned this morning but makes no difference.
Not the brew holder. It's the unit into which the brew holder fits which we are having trouble putting on the machine. This consists of a handle with a cup at one end into which the brew holder fits. The cup end is attached to the machine by means of a grooved circle. When properly attached the handle should stick out from the machine at a 90 degree angle, however the cup holder will only turn 45 degrees.
Thank, we will give this a go although we have more or less done this, but have not tried the vegetable oil.