How to fix Belle Minimix 150 which just hums?

Little used Minimix 150 240v bought new 2002ish did 2 mixes yesterday but refused to start for third mix. When I press the green button I just get a humming noise. The drum will not rotate by hand. If I manually rotate the pulley the drum does turn. Mixer had not been used for 3 years: I forgot at least 2 rules: I put the mix in b4 starting motor & emptied with it stopped. Does this sound terminal or is it obvious to those with normal brain cell levels what needs fixing? many thanks. Model No 234709M16A made 2001