If you are engraving flat items, you can lock the head height and remove the nose cone, but it should not effect the impact in this way.
My 'checklist' for this would be:
- Try different material (ie Polished metal works best)
Turn off the machine, remove the head, take off the nose cone and give it a good clean.
Re Calibrate the head (MPX-90 Head manager)
Check you are using the correct settings (ie Brass, Steel) in the driver settings.
- Print but adjust the Gamma in the Print Preview, default is 0.5 - so move up to 0.9 and see if it is better.
If you are printing on Brass, try the Steel settings as it is a harder impact.
It all depends on the material used, but the heads can do about 2100 'inch square' photographs in it's life, however as the diamond looses it's sharpness over time, the results may change.
If you use High Quality setting or Photo Setting this number will change too, it all depends on the dpi.