those 'modulators' were one of several ill-conceived attempts at 'softening' v-brakes, which were so much stronger than the typical bicycle brakes that people were launching themselves over their handlebars.

Get some Shimano Alivio grade v-brakes and be done with it. they come in silver or black. will be a bolt on replacement. figure about $20 each end for new. Do be prepared for some massively powerful braking, I use them with '2-finger' style brake levers as they are so strong.