Panasonic washing machine leaking from soap drawer

Hi,
I have a customer with a Panasonic washing machine NA-127VB4 and its leaking from the soap drawer. It doesn’t do it every time but i have seen it happen.
At first I thought it may be the pressure, so I turned the pressure down, no change. I then changed the double valve but still no change.
I have checked the drawer for blockage, it syphons well. I also checked the dispenser hose and the jets. Absolutely clear.
I know if this was a hotpoint, I would change the dispenser unit but Ive not had much experience with the panasonic. It looks a simple enough machine but never had a problem like this yet.

If anybody can point me in the right direction before I buy a dispenser and drawer , it would really be appreciated.

Thanks

Nick