Hi guys, I have a problem with my rear brakes binding, the NS wheel especially.

I've noticed that after the foot brake or handbrake has been pressed and released, the pads are still quite firmly gripping the disc. If I grab the back of the piston and pull it towards the front of the car, you can feel a little 'nudge' and the disc is free to spin again. Its almost as if the caliper is turning a little as it applies pressure to the pads and then because its skewed a little, its locked in that position.

Is it likely something to do with the sliders allowing too much play and not keeping the piston in alignment with the rest of the brake assembly as it applies pressure or something else?

Thanks

It could be simply the pads actually sticking in the slides. (dirt and rust). Cleaning these and relubing is not a fiat service procedure but well worth doing each service. Use copper slip.
The handbrake cable also tends to stick , remember the n/s is close to the exhaust and gets quite hot.
This problem has been reported often on the forum , it might be useful to do a search for other ideas.

I tried cleaning up the pads and calipers and lubing them up with copper grease. It certainly helped a little, but theres still a binding after brake has been applied (which still releases when the caliper is pulled.)

The levers on the backs of the calipers for the handbrake seem to return to the right position after using the handbrake and the problem occurs if you just use the foot brake too so i can't see it being cables related unfortunately.

I'm now starting to wonder if the pads have worn to a slight angle due to not being lubricated enough and thats whats causing the piston to shift to a slight angle and then lock on in that mis-aligned position. There is no noticeable angle on pad wear though, but it could be very slight yet enough to cause this problem?

you might be on the mark there. Although don't rule out new calipers or new sliders as the sliders might now be worn. You can probably buy a slider refurb kit, but as you have suggested, whack in some new pads and see if that fixes it. If not, refurb the calipers...

The pads need renewing anyway so I'll pop some new ones in and see. They were only done 18 months ago though so this binding could have been happening for a while its only the last couple of days it seems to have become so bad that I've noticed it.

Has anyone used one of those 'cube' rewind tools? will it do the trick?

Also, anyone know how to remove the slider pins? I noticed they do seem to have a small amount of side-to-side play in them. I'm not sure how much play they have anyway though (if any?)

Don't even bother with a cube rewind tool, utter rubbish! Get a proper re-wind kit, only about £20 on Amazon these days, well worth it.

First time I attempted the back brakes it took me 6 hours with a cube, which I eventually ditched and ended up rigging up a tool with an angle grinder tool.

Second time I did the back brakes (just recently) I used a proper re-wind kit and I did the job in 3 hours (not bad considering it took me 2 1/4 hours to do one side which was seized).