My Dyson (very first model) seems to have lost suction?

Hi, the sole plate broke on my Dyson (very first model Yellow) so I purchased a brand new one but since fitting it on to the machine the vacuum seems no longer to suck. It has suction from the hose extention but not for the sole plate. Any ideas? Please help, I cant afford a new vac and my home looks terrrible!

Many thanks in advance, KAren Moore