Can you take photo's of the caliper...what's wrong with it? looks like someone has tried to work on it before and made a real mess, the piston is scored and a bit rusty, the pin is bent, the seal, well there wasn't one and my local guy says it is a bit 'floppy'. the pads point outwards at the front so only the back of them actually hits the disc. so we think it will be best to get another one. Right....all the piston does is support the seal and therefore can be polished...pins can be replaced/straightened...seal would need replacing anyway..where the pads sit obviously needs cleaning up possibly with a soft file... All of these things can be put right... Try to fix and learn at the same time...you've got access to lots of experience and advice on this forum....use it..