Rear Brake lockup

Might not help but maybe it will? Those Packing seals came with different Kawasaki part numbers because of the change within but are identical, 43049-002 and 43049-1098. Make sure you clean off all the residue left in the caliper seal land, i use a curved dental pick but anything that gets underneath the shadowed area will work. Note there is a cut-out relief central to the seal bore, that's where a sharp but blunt tool comes in handy to get the old crap out. Check your "chrome plated" piston for pitting!! If it's flaking chrome/pitted where the packing seal resides, like one shown,      in bore it's going to forever leak. I always use assembly red rubber grease when doing mine but you might not have any?? Also check that rubber brake line for good measure. I've seen plenty of them internally plug-up with crap preventing fluid from flowing properly.