Sticky caliper?

[lietuviai]

I've been battling a repeating problem for the last several months on my 123 coupe. The left front caliper appears to be sticking or not retracting enough. I've rebuilt the front calipers thinking that was the problem. Nope.
Ive changed the brake hoses. No change.
I've beveled the pad material and even ground the metal on the pads thinking the pads were sticking in the caliper. The last ideas helped for a few hundred miles but its coming back again. The wheel bearings appear OK. I didn't seem to get any play in the wheel on the spindle.
I'm getting frustrated to the point of thinking about buying new calipers and pads. But before I blow the dough on new calipers I'd like to get some advice here. Maybe I'm overlooking something very basic?
Any ideas would be greatly appreciated.