Yes the rectifier pack could have expired , first did you check the wiring , switch ignition on and disconnect the small terminal hopefully this may turn the light off , the thick wire is positive , to fit a rectifier is guess work unless you have access to a test bench , did you put an ammeter in circuit , if you get a reading this may give an indication to what is wrong , low vaults no amps could be rectifier or regulator , in rare cases the stator, i have been out of the trade for over 17 years , but some components cant have changed , and any help i can give i will do so , if the wiring checks out fit a new one , if cost effective .