Not necessarily true. The bearings could have worn slightly, or the stem could have slipped on the steerer. The star nut can break and nothing would happen, it's only there to tension the headset, not take any load. And don't just tighten up the topcap bolt, that will damage the star nut. Undo the stem bolts so they're slack, then nip the topcap bolt up which should take up all the slack, then tighten the stem bolts up. I'd take the lever blade off first and see if the TPA has broken, if it has, replace it with a bolt. If it hasn't, replace it with a bolt anyway as the standard ones are shite. It may be that you've simply used up all of the movement in the TPA. If it isn't broken then wind it all the way in and set up the slaves again and set the pads closer to the rim. If the lever feels really mushy like there is air in the brake, then you rebleed it.