All of the above rely on the security of the Euro Cylinder to hold them in place. Old or contract cylinders have very little security. All cylinders should be British Standard with a sacrificial section that will snap off and still leave the cylinder secure. They should also be a flush fit to the handle with as little as possible protruding on the outside. See the video below explaining how easy it is for a burglar to snap your lock “weakness”
Struggling to lift the handle or turn the key – if the door drops all the locking points will be out of alignment, this puts excessive stress on the centre gearbox which will soon break under the strain, it’s much cheaper to have it adjusted now.