My dyson seems to lose suction when I switch from hose (great suction )to base

You most likely have some debris caught in the base of the unit,remove the base plate and clean out the fibers or whatever is not part of the mechanism.

You might also try to use a coat hanger to do this,where the hose gets inserted,push the hanger down through the opening and see if there is some clog that you can remove(bend the end of the hanger to be able to remove what it hooks)