Why did my back paddles stop working

Hi! So my controller got dropped one too many times and i this isn't the first controller ive had to fix i just don't know exactly what to do in this case. Ive got stick drift but that's as easy as open, pop out old part, put new part in. No in this case the back right paddles when you're holding it just stopped one day. Both of them. The left ones work and no other button has problems, well besides the A getting sticky or slow just from a lot of use. And idk if it's cheaper to fix or buy one outright because idk if it is fixable