Help is it possible to fix a vax rapid classic carpet cleaner with issues p?

Hi Can anyone help i have a vax rapid classic carpet washer motor works fine sounds powerfull problem i cant figure out how to fix it has water/cleaner doesnt seem to be getting through to lift off tank there is a round plastic circle that washer tank fits in this just keeps leaking i dont know if its ok to try force this cap off im convinced problem is underneath??????Can anyone recommend a vax cheap repairer in hampshire please????Best Regards Marie.