In that picture of the master it almost looks like the rear line is flattened out at the bend. I'm guessing you checked the whole back line for and bends or restrictions. If you bled them then they are not blockes off but could be restricted.
in that picture it does look like they're bent, but it's not. that's shadows making it look like that. I haven't checked the whole back lines, but I can tomorrow.
If the line in the back is restricted, wouldn't that cause them to not respond as well? Instead of responding too much?
@PeterM yup, that's what we did - Got it till it's just grabbing, and then back it off till it spins freely. So if that's how to properly adjust the back brakes, then it's been done.
I think it's the proportioning valve has either got crap in it (from the rubber rotting in everything else) or it's got problems. Anyone have a good picture of what the valve looks like?
I'm probably gonna replace it, and see if that's it. If that ain't it, then I'm gonna try the rubber hoses next.