probloms my rear calipers are binding whats the usual suspects?

[s12-newbie]

the wheels are binding to turn when its jacked up with the handbrake off, gonna investigate the handbrake mech! i think it could be that! i fookin hope so :/

i'm giving my silvia a little refurb whilst i'm at it, i'll get some pics,
i'm doing the sills as they are grotty on the outside but when i cut the outer sill away inside is mint :/ strange but i have new sills to weld on

front wings are frilly but i have steel to fix them so aslong as i can sort the brakes i'll be on my way to a new MOT