I've been trying to push back the calipers to my 91 s13. I bought a special key to push them back...

I'm not sure if the calipers are working properly, any suggestions?

if you've been trying to push it back with your hand its not going to happen, with the tool it should slide back in fairly easliy what i do is take the old brake pad and hammer it back in as for it not working properly its kinda vauge but checking the seal around the piston for leaks or damage is a good start.