Helping my buddy solve an emergency brake problem on his 67 Fastback. He has 9 inch reaerend with factory drum brakes. The rear brakes are adjusted fine such that on jack stands, car running and in drive, he applies the brake pedal and the tires stop as they should. If he uses the emegency brake and pulls as far as it will extend, the tires don't even slow down, never mind stop. Now before you say just adjust the emergency brake cables, been there and done that. Have removed all slack from the cables and no difference. We have also verified that the cables are not stuck. We remove the brake drum and actuate the e-brake handle and you can see the cable pulls on the e-brake lever on the backing plate and the shoes move outward. The issue is it doesn't seem to be using enough force to move the shoes enough to stop the wheels from turning. A good friend of ours has a family garage where they have done hundreds of brake jobs and he could not diagnose the problem either. Aynone have some suggestions about what to check? Seems to me that the hydraulic slave wheel cylinders are working fine, but whatever mechanical mechanism is responsible for moving the e-brake is not applying enough force. Thanks in advance for any help.