front brake grabbing (locking)

[wlf89]

got a 67 chevy c10 which has 4 wheel drum brakes. other day when pulling out of drive the brakes sounded like they where holding, figured out it was the front left brake making the noise. jacked the truck up, and it will spin for as long as i go backwards, but will only spin two or three rounds before it locks up if i spin it forward. took wheel and drum off and everything looks good, drum, shoes, hardware everything looks good. dont see no leaks nowhere and the fluid is still full in the master. went ahead and bleed the left side while i was there looking at it but didnt make no difference. have replaced master cylinder, wheel cylinders,brake shoes,and drums, and new hardware kit in the last 4 months.