How can I fix my Vax model Rapide 1520?

I have a Vax Rapide 1520 and I use it to clean carpets in my house(using its water facility) around 5 times a year, but now the water is not able to be sucked up from its container to vacuum hose. I dismantled the vacuum cleaner and saw that the water tubings are well installed and I assume it is the water pump problem. Can anyone suggest from where I can buy this pump for this model

thanks