LOOK PP176 repair?

I have a pair of old Look clipless pedals onmy bike. These are my first clipless pedals, so I'm not
sure if they are working correctly. I have the tension adjustment set as low as it will go-the
screws took quite a bit of lube to loosen up, sounds as if there is a fair bit of grit and grime in
the pedals. They clip in and release smoothly and lightly now. The problem is that if I pedal hard
and turn my foot just a bit, there is a fairly loud click and a feeling as if the cleats are seating
in. Almost as if they were not fully connected at first. After this happens the cleats are quite
difficult to disengage fromt he pedals. The situation of expecting to have a light smooth release,
only to have the pedals stick and require a big tug/twist to get out of them is not very safe. Any
ideas on what the problem might be? Hope to salvage them, but maybe I'llhave to get new pedals. Paul