Pump Problem

[computerman]

I have a pump 24 ltr expansion vessel, feeding 4 flats. The pump has been acting up for a while (wont turn off) . I replaced expansion vessel and pressure switch. Went to prime the unit, but found pump full of water, but no water in expansion vessel. Pressure guage runs at 1.9 bar and factory setting is set at 1.9 bar.

I think I need to get water into the vessel, how is this done?
any help appreciated.