Pumping

So when i pump i get a good amount out of one breast, but on the other one i get not even half as much! i don’t know what to do. it’s almost like it doesn’t go through “let down”. there’s no squirting of milk out of it. just little drops. it used to do just as well as the other but in the last three or so weeks it’s been not getting as much and i don’t know what to do to help it get back up to where it used to be! any tips would be greatly appreciated.