Jetwashed the block paving yesterday. Came to shut the up and over garage door last night and ut wouldn't close! Damn! Have the blocks lifted a bit - took hammer and block of wood to bash them - no change.
Today I looked from inside the garage and found the pullcord with a knob on the end had stretched (or the knot had slipped) and the knob was getting trapped between door and small step (1/2 inch) into garage.
Moved knot - - job done.