My parents' Barratt house has had the same door handles on since the 70s (ish) and all their door handles are broken as the springs have gradually given up over the years. I thought they were just being lazy but having tried to replace them myself have discovered that the latch mechanism (where the spindle goes through) is a different size to the ones B&Q sell. Standard size seems to be 45mm from the front plate to the centre of the spindle, yet the existing are all 55mm, meaning that when I put a new mechanism in, the spindle hole is not visible. Any suggestions? Short of replacing all the doors...