I've just put my be pads in tonight and had a bit of trouble pushing the pistons in on the left calliper. Right calliper of pins and pads out. A good squirt of brake cleaner, soft bristle toothbrush scrubbed over pistons then pushed in. New pads and pins back in and calliper back no probs. Left calliper off pins and pads out, spray of cleaner. Push one piston in then push it's twin in and the first one pops back out. I don't gave a proper tool for pushing the pistons back in, but the right calliper had no issues. Anyway I got a bit of wood and pushed one pair in. Pushed the opposite pair in and the first pair came back out. Took me ages to get them out enough so I had enough room to get the new pads over the disk. Can someone in the know tell me the cause of this? Do I have dodgy seals on that side or something else? Thanks in advance