Rear wheel locks when backing up

SOURCE: when i was driving home from work my back brake

it sounds like you have run out of brake linings and the remaainder of the pads(steel backing plates)are now jammed against the disc,you will need to very carefully put a screwdriver between the disc and caliper to push the pistons back,once you have donethat you should be able to unbolt the caliper and remove it from the bike,you will need a new set of brake pads and possibly a new disc as it will no doubt be quite badly scored

SOURCE: rear brake caliper clip

its probably the anti rattle plate that fits onto the pad itself!

SOURCE: 1992 ZXR 250 Ninja locked ignition & brakelight stuck on

Try jiggling the handle bars as you turn the key to relieve the pressure off the ignition lock. The kawasaki's have one position past the off "Lock" position that is called the "Acc" this will leave your brake light on. So the key switch goes "Acc", "Lock", "On". Make sure your key is in the Lock position and not the Accesory position

SOURCE: how to fit rear brake pad retainer clip

If the clip has a slot in it then it fits in the caliper where the ends of the pads fit.
If not & it has a sprung tab then it fits in the caliper where the top of the pads fit

Hope this helps.
(If it does then please mark this as 'useful')
Ride Safe
Bike-Doc

Testimonial: "Thanks sorted i think i just needed reassuring ta."

SOURCE: On my 1986 GPZ600 the rear brake siezes up when I use it.

Sounds like you need to service the caliper. Remove the piston from the caliper by pumping the brake pedal, be warned you will get brake fluid everywhere. Remove piston seals, dust and oil, you'll probably find that the grooves where they usually reside are full of 'crud' thoroughly clean the grooves, clean the seals then inspect seals for damage and replace if necessary, grease seals (high temp grease) and put back into caliper, wipe away excess grease. Inspect piston for corrosion, minor corrosion can be flatted back with 1200 grit sandpaper, if too badly corroded replace. lightly grease piston (high temp grease) and push into caliper. the piston should slide in easily by hand. Finally bleed caliper well, flush new fluid through entire system.

Testimonial: "Thanks for that input, I never contemplated about the crud and corrosion affecting the seals and preventing the brake pistons from moving freely. "