Love it - great job Andy !
Re the focus problem - it may be that the sensor needs to be cleaned (other than any auto-clean function on the camera). Also, it may be worth removing the lens and cleaning the contacts on the lens and body. A rub over with a soft cloth should do the job. ( refer to the manual for sensor cleaning.). The front element of the lens may also require a light clean, again with an "approved" cleaning cloth - virtually invisible surface patina (even with a filter in place), will cause a degree of soft focus.
Note also that the sensor and auto-focus can sometimes be "fooled" by certain combinations of background and subject colours and lighting type and angles. Try using manual focus, with a range of shutter speeds / aperture settings, and see if this has any effect.
If this does not improve things, then it may be that the camera is nearing the end it's useful life, although probably doubtful. Average lifespan before "deep service" depends on the model, but is usually around 100,000 to possibly 200,000 shutter activations.
The current shutter count can be checked by downloading a recent (new) jpeg to one of many shutter count web sites.