OK, dropped my '91 KDX 250 off trailer in transit (first time that has happened in about 25 years of riding). This destroyed my front master cylinder. I bought a replacement from a '94 KX 250 and installed it. Same old mushy lever feel, but it worked. Went riding yesterday and the brakes quit waaaayyy back in the woods. Lever moves, no brakes. So today I bled and bled them. I was never able to get air to stop going through the tube (vaccuum bleeder). So is the master cylinder no good or is the caliper bad? I couldn't find anything loose and no fluid leaks either. Advice?