Defy Automaid Washing Machine - Does not draw washing powder into drum?

Defy Automaid (1985 purchase) front loader. Was in for waterleak repair as agents. On return, the machine does not disolve the washing powder in the dispenser and draw it into the drum. What could the cause be. It appears that the siphone is missing or the valve "timing" on the dispenser has been alter. Should it have a siphone or is it only on more recent models. Normally you can hear clearly the sucking noise of the siphone when in operation. Hope you can help