Could be any of several things. Let’s go straight to the horses mouth and see if they have a solution:
https://www.justanswer.com/sip/oster?r=ppc%7Cga%7C2%7CHI%20-%20Appliances%7COster&JPKW=www%20oster%20com&JPDC=S&JPST=&JPAD=83365223338&JPMT=b&JPNW=g&JPAF=txt&JPCD=20120207&JPRC=1&JPOP=Darren_Andrew9sec_Trans&mkwid=sT2B9s0xV_dc&pcrid=83365223338&pkw=www%20oster%20com&pmt=b&plc=&cmpid=15843262&agid=1989489538&fiid=&tgtid=kwd-457839282&ntw=g&dvc=c&gclid=EAIaIQobChMI0tvUlOez3gIVT7jACh3tjQh_EAMYASAAEgJwIfD_BwE